Support Ctrl-C to interrupt console

Long running tasks in the console cannot be interrupted from within the GUI console view (e.g. a while(1)). However, I can Ctrl-C within the terminal that I launched angr-management from and it will stop the task.

I think *the right thing* to do here is to respond to Ctrl-C (or whatever binding) as IPython would when launched from a terminal:

```
In [1]: while True:
...: pass
...:
^C---------------------------------------------------------------------------
KeyboardInterrupt Traceback (most recent call last)
in
1 while True:
----> 2 pass
3

KeyboardInterrupt:

In [2]:

```