Switched interrupt management to a new set of Trigger functions and static Trigger objects, eliminating the old InterruptQueue of constantly created/destroyed InterruptEvents

modules/pdp11/lib/cpu.js

@@ -898,6 +898,11 @@ CPUPDP11.prototype.calcRemainingTime = function()
  *
  * Why not use JavaScript's setTimeout() instead?  Good question.  For a good answer, see setTimer() below.
  *
+ * TODO: Consider making the addTimer() and setTimer() interfaces more like the addTrigger() and setTrigger()
+ * interfaces (which return the underlying object instead of an array index) and maintaining a separate list
+ * of active timers, in order of highest to lowest cycle countdown values, as this could speed up getBurstCycles()
+ * and updateTimers() functions ever so slightly.
+ *
  * @this {CPUPDP11}
  * @param {function()} callBack
  * @return {number} timer index