Flag that opens q::lastTrace on the REPL on violation

[bugarela]

There seems to be a lot of opportunity to integrate simulation and REPL better. We had a need for this specifically in a project recently and, as a workaround, we would do:

1. Copy the seed from the simulation command (PS: only possible without --out-itf, which was annoying)
2. Open the REPL and set the seed
3. Call q::test with the proper params (also very annoying)
4. Call q::lastTrace

This is a super hidden workaround that regular users would never think of. We should streamline it.

Fixing #544 should make this even more valuable.