inspector: prototype debugging by sharing "debugger" app functionality

The following features are currently supported:
- Load a recording produced with "marsyas-debug record ...".
- Compare against the recording whenever system ticked.
- Print out bugs for current tick.

To-be-implemented:
- Re-start debugging (how to rewind a MarSystem?)
- Navigate graph to source of bug when clicking into bug list.
- ...
cmake: add forgotten file