RTC progress indicator

[Robadob]

Would be useful to have something to indicate progress of runtime compilation.

Due to where RTC occurs, perhaps difficult to do a combined progress console indicator. But adding a started/finished for each agent fn would be trivial.

Even harder to pass this progress to visualiser for display.

This has become apparent from Carlos picking up James's Python predator prey, which has ~15 agent functions to be compiled on first run.

[Robadob]

This is somewhat less important with recent Jitify compile speed improvements. Agent function compilation is now down to around 1 second per agent function (down from 7+s).