Updated some javadoc.  Added some toStrings().

Fixed an error with key board events that updated the list of pressed keys in the document after the event was propagated.
Added a new state "depressed" for a button.  Changed the way the action is detected.
Fixed an error with child rendering
Added the base texture (as "no-texture") to the core registry
Fixed a couple errors with style sheet parsing.  One that raised errors when using a number for a size value and one that prevented specifying styles for anti-states (the condition of a state being false).
Forgot this with the last commit
Corrected a spelling error in lightGray
#6: Added the toggle button.  Tested.