Add: variable $displayname or $lorename - shows item or mob custom name.
Fix: mob & item $t(oolname) variables now use readable names
Fix: NPE when parsing variables with iteminhand being empty.
Minor: change "player is null or in creative mode" debug msg to EXTREME verbosity
Fix: playerinteractevents already cancelled should not be uncancelled. Fixes issue #223.

* need to process cancelled events to support interactions with air.
* added safety so that any event.setCancelled(fasle) gets intercepted and ignored if this is a cancelled event.