INT 15 - MultiDOS Plus - TRIGGER EVENT                                          
	AX = 1E01h
	DX = event/trigger number (00h-3Fh)
Return: AH = status
	    00h successful
	    01h invalid event/trigger number
Notes:	schedules any task waiting for event; if no task is waiting, the event
	  counter is incremented (and will roll over if it was 65535)
	may be invoked by interrupt handler
SeeAlso: AX=1E00h,AX=1E02h