Completely rework with_fx logic (again). Remove all (known) resource leaks:
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...
jweather/sonic-pi,jweather/sonic-pi,jweather/sonic-pi,jweather/sonic-pi,jweather/sonic-pi