macOS OpenGL crash race condition

During my attempts to build standalone binaries of the CQ-Editor for macOS, I have discovered at least two mechanisms for the app to crash at launch. Both are related to OpenGL not being initialized. The first mechanism might be related to #106 and involve a race condition:

1. `MainWindow`'s `__init__` method calls `self.components['object_tree'].addLines()`
2. This triggers an event ` self.sigObjectsAdded.emit(ais_list)`
3. which is responded by `def display_many(self,ais_list,fit=None):` in `viewer.py`
4. This calls `context.Display(ais)` which resolves to the `Display` method of `OCC.Display.qtDisplay.qtViewer3d` which resolves to `_AIS.AIS_InteractiveContext_Display(self, *args)`

This last call to AIS display occurs before the thread responsible for initializing the OpenGL driver and display context. We infer this is the case since we see no evidence of the initialization completed (usually a console message saying something about the layer manager).

There are definitely non thread safe conditions being established at application launch, especially the call to add the axis lines. When this is commented out, the app may or may not crash depending on the launch context (i.e. direct from terminal, lldb, or via the macOS `launchd` when initiated by the Finder or the terminal `open` command).

The support stack trace is as follows...

```shell
* thread #1: tid = 0x34ddc4, 0x00007fff670247fa libsystem_kernel.dylib`__pthread_kill + 10, name = 'ZMQbg/1', queue = 'com.apple.main-thread', stop reason = signal SIGABRT
thread #2: tid = 0x34de09, 0x00007fff6701f92e libsystem_kernel.dylib`__workq_kernreturn + 10
thread #5: tid = 0x34df34, 0x00007fff6701f92e libsystem_kernel.dylib`__workq_kernreturn + 10
thread #6: tid = 0x34df44, 0x00007fff67020ce6 libsystem_kernel.dylib`__psynch_cvwait + 10
thread #7: tid = 0x34df48, 0x00007fff67022bce libsystem_kernel.dylib`kevent + 10
thread #8: tid = 0x34df49, 0x00007fff67022bce libsystem_kernel.dylib`kevent + 10
thread #9: tid = 0x34df4a, 0x00007fff67022bce libsystem_kernel.dylib`kevent + 10
(lldb) thread list all
Process 94969 stopped
* thread #1: tid = 0x34ddc4, 0x00007fff670247fa libsystem_kernel.dylib`__pthread_kill + 10, name = 'ZMQbg/1', queue = 'com.apple.main-thread', stop reason = signal SIGABRT
thread #2: tid = 0x34de09, 0x00007fff6701f92e libsystem_kernel.dylib`__workq_kernreturn + 10
thread #5: tid = 0x34df34, 0x00007fff6701f92e libsystem_kernel.dylib`__workq_kernreturn + 10
thread #6: tid = 0x34df44, 0x00007fff67020ce6 libsystem_kernel.dylib`__psynch_cvwait + 10
thread #7: tid = 0x34df48, 0x00007fff67022bce libsystem_kernel.dylib`kevent + 10
thread #8: tid = 0x34df49, 0x00007fff67022bce libsystem_kernel.dylib`kevent + 10
thread #9: tid = 0x34df4a, 0x00007fff67022bce libsystem_kernel.dylib`kevent + 10
(lldb) thread backtrace all
* thread #1, name = 'ZMQbg/1', queue = 'com.apple.main-thread', stop reason = signal SIGABRT
* frame #0: 0x00007fff670247fa libsystem_kernel.dylib`__pthread_kill + 10
frame #1: 0x00007fff670e1bc1 libsystem_pthread.dylib`pthread_kill + 432
frame #2: 0x00007fff66faba1c libsystem_c.dylib`abort + 120
frame #3: 0x00007fff670a1647 libsystem_malloc.dylib`malloc_vreport + 548
frame #4: 0x00007fff670a440e libsystem_malloc.dylib`malloc_report + 151
frame #5: 0x000000010d851d69 libc++abi.1.dylib`__cxa_end_catch + 137
frame #6: 0x000000012d3e45a4 _AIS.so`_wrap_AIS_InteractiveContext_Display__SWIG_0(_object*, int, _object**) + 1332
frame #7: 0x000000012d2ad902 _AIS.so`_wrap_AIS_InteractiveContext_Display(_object*, _object*) + 98
frame #8: 0x000000010192bff3 libpython3.7m.dylib`_PyMethodDef_RawFastCallKeywords + 259
frame #9: 0x000000010192bbd2 libpython3.7m.dylib`_PyObject_FastCallKeywords + 306
frame #10: 0x0000000101a34244 libpython3.7m.dylib`call_function + 708
frame #11: 0x0000000101a2b3d5 libpython3.7m.dylib`_PyEval_EvalFrameDefault + 7893
frame #12: 0x0000000101a2906c libpython3.7m.dylib`_PyEval_EvalCodeWithName + 3308
frame #13: 0x000000010192afd1 libpython3.7m.dylib`_PyFunction_FastCallDict + 481
frame #14: 0x000000010192ca84 libpython3.7m.dylib`_PyObject_Call_Prepend + 164
frame #15: 0x000000010192e494 libpython3.7m.dylib`method_call + 36
frame #16: 0x000000010192c496 libpython3.7m.dylib`PyObject_Call + 246
frame #17: 0x00000001082dd007 QtCore.so`PyQtSlot::call(_object*, _object*) const + 39
frame #18: 0x00000001082dcf16 QtCore.so`PyQtSlot::invoke(void**, _object*, void*, bool) const + 374
frame #19: 0x00000001082dcfac QtCore.so`PyQtSlot::invoke(void**, _object*, void*) const + 12
frame #20: 0x00000001082dfe0b QtCore.so`qt_metacall_worker(_sipSimpleWrapper*, _typeobject*, _sipTypeDef*, QMetaObject::Call, int, void**) + 683
frame #21: 0x00000001082dfb32 QtCore.so`qpycore_qobject_qt_metacall(_sipSimpleWrapper*, _sipTypeDef*, QMetaObject::Call, int, void**) + 66
frame #22: 0x000000010586b37d QtCore`QMetaObject::activate(QObject*, int, int, void**) + 1773
frame #23: 0x00000001082d971f QtCore.so`pyqtBoundSignal_emit(_object*, _object*) + 655
frame #24: 0x000000010192bff3 libpython3.7m.dylib`_PyMethodDef_RawFastCallKeywords + 259
frame #25: 0x0000000101936885 libpython3.7m.dylib`_PyMethodDescr_FastCallKeywords + 85
frame #26: 0x0000000101a34274 libpython3.7m.dylib`call_function + 756
frame #27: 0x0000000101a2b3bb libpython3.7m.dylib`_PyEval_EvalFrameDefault + 7867
frame #28: 0x000000010192b94e libpython3.7m.dylib`function_code_fastcall + 254
frame #29: 0x0000000101a3424e libpython3.7m.dylib`call_function + 718
frame #30: 0x0000000101a2b3d5 libpython3.7m.dylib`_PyEval_EvalFrameDefault + 7893
frame #31: 0x0000000101a2906c libpython3.7m.dylib`_PyEval_EvalCodeWithName + 3308
frame #32: 0x000000010192afd1 libpython3.7m.dylib`_PyFunction_FastCallDict + 481
frame #33: 0x000000010192ca84 libpython3.7m.dylib`_PyObject_Call_Prepend + 164
frame #34: 0x000000010199431a libpython3.7m.dylib`slot_tp_init + 298
frame #35: 0x000000010199da17 libpython3.7m.dylib`type_call + 295
frame #36: 0x000000010192bd53 libpython3.7m.dylib`_PyObject_FastCallKeywords + 691
frame #37: 0x0000000101a34244 libpython3.7m.dylib`call_function + 708
frame #38: 0x0000000101a2b466 libpython3.7m.dylib`_PyEval_EvalFrameDefault + 8038
frame #39: 0x000000010192b94e libpython3.7m.dylib`function_code_fastcall + 254
frame #40: 0x0000000101a3424e libpython3.7m.dylib`call_function + 718
frame #41: 0x0000000101a2b466 libpython3.7m.dylib`_PyEval_EvalFrameDefault + 8038
frame #42: 0x0000000101a2906c libpython3.7m.dylib`_PyEval_EvalCodeWithName + 3308
frame #43: 0x0000000101a28370 libpython3.7m.dylib`PyEval_EvalCode + 48
frame #44: 0x0000000100003116 CQ-Editor`___lldb_unnamed_symbol20$$CQ-Editor + 342
frame #45: 0x0000000100003621 CQ-Editor`___lldb_unnamed_symbol27$$CQ-Editor + 385
frame #46: 0x0000000100001de4 CQ-Editor`___lldb_unnamed_symbol1$$CQ-Editor + 52
thread #2
frame #0: 0x00007fff6701f92e libsystem_kernel.dylib`__workq_kernreturn + 10
frame #1: 0x00007fff670de760 libsystem_pthread.dylib`_pthread_wqthread + 390
frame #2: 0x00007fff670dd827 libsystem_pthread.dylib`start_wqthread + 15
thread #5
frame #0: 0x00007fff6701f92e libsystem_kernel.dylib`__workq_kernreturn + 10
frame #1: 0x00007fff670de760 libsystem_pthread.dylib`_pthread_wqthread + 390
frame #2: 0x00007fff670dd827 libsystem_pthread.dylib`start_wqthread + 15
thread #6
frame #0: 0x00007fff67020ce6 libsystem_kernel.dylib`__psynch_cvwait + 10
frame #1: 0x00007fff670e2185 libsystem_pthread.dylib`_pthread_cond_wait + 701
frame #2: 0x0000000101a8ae88 libpython3.7m.dylib`PyThread_acquire_lock_timed + 440
frame #3: 0x0000000101aeb9af libpython3.7m.dylib`acquire_timed + 431
frame #4: 0x0000000101aebaed libpython3.7m.dylib`lock_PyThread_acquire_lock + 61
frame #5: 0x000000010192c1e3 libpython3.7m.dylib`_PyMethodDef_RawFastCallKeywords + 755
frame #6: 0x0000000101936885 libpython3.7m.dylib`_PyMethodDescr_FastCallKeywords + 85
frame #7: 0x0000000101a34274 libpython3.7m.dylib`call_function + 756
frame #8: 0x0000000101a2b3bb libpython3.7m.dylib`_PyEval_EvalFrameDefault + 7867
frame #9: 0x0000000101a2906c libpython3.7m.dylib`_PyEval_EvalCodeWithName + 3308
frame #10: 0x000000010192bed6 libpython3.7m.dylib`_PyFunction_FastCallKeywords + 230
frame #11: 0x0000000101a3424e libpython3.7m.dylib`call_function + 718
frame #12: 0x0000000101a2b3bb libpython3.7m.dylib`_PyEval_EvalFrameDefault + 7867
frame #13: 0x0000000101a2906c libpython3.7m.dylib`_PyEval_EvalCodeWithName + 3308
frame #14: 0x000000010192bed6 libpython3.7m.dylib`_PyFunction_FastCallKeywords + 230
frame #15: 0x0000000101a3424e libpython3.7m.dylib`call_function + 718
frame #16: 0x0000000101a2b3bb libpython3.7m.dylib`_PyEval_EvalFrameDefault + 7867
frame #17: 0x000000010192b94e libpython3.7m.dylib`function_code_fastcall + 254
frame #18: 0x0000000101a2b745 libpython3.7m.dylib`_PyEval_EvalFrameDefault + 8773
frame #19: 0x0000000101a2906c libpython3.7m.dylib`_PyEval_EvalCodeWithName + 3308
frame #20: 0x000000010192bed6 libpython3.7m.dylib`_PyFunction_FastCallKeywords + 230
frame #21: 0x0000000101a3424e libpython3.7m.dylib`call_function + 718
frame #22: 0x0000000101a2b466 libpython3.7m.dylib`_PyEval_EvalFrameDefault + 8038
frame #23: 0x000000010192b94e libpython3.7m.dylib`function_code_fastcall + 254
frame #24: 0x0000000101a3424e libpython3.7m.dylib`call_function + 718
frame #25: 0x0000000101a2b3bb libpython3.7m.dylib`_PyEval_EvalFrameDefault + 7867
frame #26: 0x000000010192b94e libpython3.7m.dylib`function_code_fastcall + 254
frame #27: 0x0000000101a3424e libpython3.7m.dylib`call_function + 718
frame #28: 0x0000000101a2b3bb libpython3.7m.dylib`_PyEval_EvalFrameDefault + 7867
frame #29: 0x000000010192b94e libpython3.7m.dylib`function_code_fastcall + 254
frame #30: 0x000000010192ca84 libpython3.7m.dylib`_PyObject_Call_Prepend + 164
frame #31: 0x000000010192e494 libpython3.7m.dylib`method_call + 36
frame #32: 0x000000010192c496 libpython3.7m.dylib`PyObject_Call + 246
frame #33: 0x0000000101aeae19 libpython3.7m.dylib`t_bootstrap + 169
frame #34: 0x0000000101a8aa57 libpython3.7m.dylib`pythread_wrapper + 39
frame #35: 0x00007fff670e1e65 libsystem_pthread.dylib`_pthread_start + 148
frame #36: 0x00007fff670dd83b libsystem_pthread.dylib`thread_start + 15
thread #7
frame #0: 0x00007fff67022bce libsystem_kernel.dylib`kevent + 10
frame #1: 0x000000012fa871fb libzmq.5.dylib`zmq::kqueue_t::loop() + 283
frame #2: 0x000000012fab76df libzmq.5.dylib`thread_routine(void*) + 63
frame #3: 0x00007fff670e1e65 libsystem_pthread.dylib`_pthread_start + 148
frame #4: 0x00007fff670dd83b libsystem_pthread.dylib`thread_start + 15
thread #8
frame #0: 0x00007fff67022bce libsystem_kernel.dylib`kevent + 10
frame #1: 0x000000012fa871fb libzmq.5.dylib`zmq::kqueue_t::loop() + 283
frame #2: 0x000000012fab76df libzmq.5.dylib`thread_routine(void*) + 63
frame #3: 0x00007fff670e1e65 libsystem_pthread.dylib`_pthread_start + 148
frame #4: 0x00007fff670dd83b libsystem_pthread.dylib`thread_start + 15
thread #9
frame #0: 0x00007fff67022bce libsystem_kernel.dylib`kevent + 10
frame #1: 0x00000001030edf07 select.cpython-37m-darwin.so`kqueue_queue_control + 903
frame #2: 0x000000010192bff3 libpython3.7m.dylib`_PyMethodDef_RawFastCallKeywords + 259
frame #3: 0x0000000101936885 libpython3.7m.dylib`_PyMethodDescr_FastCallKeywords + 85
frame #4: 0x0000000101a34274 libpython3.7m.dylib`call_function + 756
frame #5: 0x0000000101a2b3bb libpython3.7m.dylib`_PyEval_EvalFrameDefault + 7867
frame #6: 0x0000000101a2906c libpython3.7m.dylib`_PyEval_EvalCodeWithName + 3308
frame #7: 0x000000010192bed6 libpython3.7m.dylib`_PyFunction_FastCallKeywords + 230
frame #8: 0x0000000101a3424e libpython3.7m.dylib`call_function + 718
frame #9: 0x0000000101a2b3bb libpython3.7m.dylib`_PyEval_EvalFrameDefault + 7867
frame #10: 0x000000010192b94e libpython3.7m.dylib`function_code_fastcall + 254
frame #11: 0x0000000101a3424e libpython3.7m.dylib`call_function + 718
frame #12: 0x0000000101a2b3bb libpython3.7m.dylib`_PyEval_EvalFrameDefault + 7867
frame #13: 0x000000010192b94e libpython3.7m.dylib`function_code_fastcall + 254
frame #14: 0x0000000101a3424e libpython3.7m.dylib`call_function + 718
frame #15: 0x0000000101a2b3bb libpython3.7m.dylib`_PyEval_EvalFrameDefault + 7867
frame #16: 0x000000010192b94e libpython3.7m.dylib`function_code_fastcall + 254
frame #17: 0x0000000101a3424e libpython3.7m.dylib`call_function + 718
frame #18: 0x0000000101a2b3bb libpython3.7m.dylib`_PyEval_EvalFrameDefault + 7867
frame #19: 0x000000010192b94e libpython3.7m.dylib`function_code_fastcall + 254
frame #20: 0x000000010192ca84 libpython3.7m.dylib`_PyObject_Call_Prepend + 164
frame #21: 0x000000010192e494 libpython3.7m.dylib`method_call + 36
frame #22: 0x000000010192c496 libpython3.7m.dylib`PyObject_Call + 246
frame #23: 0x0000000101a2b745 libpython3.7m.dylib`_PyEval_EvalFrameDefault + 8773
frame #24: 0x000000010192b94e libpython3.7m.dylib`function_code_fastcall + 254
frame #25: 0x0000000101a3424e libpython3.7m.dylib`call_function + 718
frame #26: 0x0000000101a2b3bb libpython3.7m.dylib`_PyEval_EvalFrameDefault + 7867
frame #27: 0x000000010192b94e libpython3.7m.dylib`function_code_fastcall + 254
frame #28: 0x0000000101a3424e libpython3.7m.dylib`call_function + 718
frame #29: 0x0000000101a2b3bb libpython3.7m.dylib`_PyEval_EvalFrameDefault + 7867
frame #30: 0x000000010192b94e libpython3.7m.dylib`function_code_fastcall + 254
frame #31: 0x000000010192ca84 libpython3.7m.dylib`_PyObject_Call_Prepend + 164
frame #32: 0x000000010192e494 libpython3.7m.dylib`method_call + 36
frame #33: 0x000000010192c496 libpython3.7m.dylib`PyObject_Call + 246
frame #34: 0x0000000101aeae19 libpython3.7m.dylib`t_bootstrap + 169
frame #35: 0x0000000101a8aa57 libpython3.7m.dylib`pythread_wrapper + 39
frame #36: 0x00007fff670e1e65 libsystem_pthread.dylib`_pthread_start + 148
frame #37: 0x00007fff670dd83b libsystem_pthread.dylib`thread_start + 15
```