Teach Promise#deliver! to not raise an exception if required.
Allow synths to sneakily be added to tracker without blowing things up.

This is possible (in a with_fx block), although extremely unlikely. 
The UDP packet would need to be delayed by more than half a second...
update example to new syntax style
update blue monday example to new syntax style
update comps beats example to new syntax style
Completely rework with_fx logic (again). Remove all (known) resource leaks:

* GC now guaranteed to execute
* trackers created within no_kill block
* only issue is having to sleep before blocking on trackers. This is to
  allow roundtrip time for synth trigger notification. 
  This could be improved with more thought...