[stringtemplate-interest] ugh. STViz updated

[Terence Parr]

took me forever but I've gutted how i tracked debugging events and hacked on STViz forever. swing is weird.  Not much forward progress but...

* refactored to fold DebugST into ST; adds one object ptr to every ST
  instance but worth reduction in complexity. "new ST(...)" calls didn't
  work (not DebugST objects) in inspector.  ST.inspect() for any ST now.
* Fixed bug in STViz. Didn't highlight entire output when you click
  topmost template.
* STGroup.debug no longer there nor static.  It's an instance var of
  Interpreter.  ST.inspect() tells interp to debug. STGroup.trackCreationEvents
  says to record where in code an ST was created and where code added attributes.
* Gutted tree model for STViz, refactored debugging/event tracking code.
* creation events had wrong location (launch of interp location); only tracks
  now for externally/injected created templates.

Ter