Debugging while running

[nbbm26]

Breakpoint integration desired for gdb pytest or something. Not impossible, looking to contribute to this and possibly other issues.

[serwy]

The IDLE debugger is complicated and fragile due to its history of first being an in-process debugger before IDLE gained its subprocess capabilities, and then proxying results through its RPC. It needs to be re-written before pytest and gdb integration can be done.