change format for display of schedule items
added a method to cause a stable state reevaluation when a trigger fires
added a fix to execute a subcondition command if it's condition has fired when the next stable state evaluation is tested
  TBD this should probably be done by pushing a message handler for the trigger instead.
removed a conservative flagging of a need to recheck stable states. Needs more testing
added notes on more things to be done
fixed incorrect use of null trigger in previous commit
added a couple of inverter mathines