More straightforward usage

Currently these 3 steps are required to use hxcpp-debugger:
1. add `-lib hxcpp-debugger`
2. add `-D HXCPP_DEBUGGER`
3. add `new debugger.HaxeRemote(true, "localhost");` to the entry point

It would be nice if this could be reduced to just the first step.

Eliminating step 2 should be simple, either via an `extraParams` file that automatically defines `HXCPP_DEBUGGER` if the lib is included, or just by using the define that is added for the haxelib instead. I can't really think of a situtation where you would want to include the lib, but not define `HXCPP_DEBUGGER`?

The code needed could be injected via a macro somehow. @RealyUniqueName pointed out that alternatively, static var initialization could be abused for this.
There would still need to be a way to manually set the host IP somehow for remote debugging of course.

(discussed in haxe-dev, cc @Simn / @nadako)