Implemented a significant portion of the NewtRepaint manager and
listeners.

Simply swap the event listener in GLG2DWindow to see the results.

Currently paintImmediately is not supported, which I think is what we
want. Need to discuss with Brandon.
This class should not be using the custom Repaint Manager.
Attempts to rework the repaint manager with little success. 

Added some documentation to various places.
GLContext is no longer globally available from GLGraphics2D.
AbstractDrawHelpers can access drawing contexts using getGL(..).