Debugger: handle live modifications

[obycode]

trafficstars

It would be cool if the user could modify the clarity code while in the middle of a debug session and the new code is executed.

[moodmosaic]

:thinking: I can't remember if I've ever seen this fully working anywhere; usually it's working partially―once the edits are non-trivial they won't get picked up and/or the breakpoints will get messed. Perhaps that won't be the case here.