excessive dirty flag setting corrected
added factories for translate and scale
changed children dirty behavior

For now when a Node becomes dirty so does its children. At the moment I
am considering aabboxes an upward traversal and transforms a downward
traversal.
removed dead code
minor reordering but not critical.
inprogress
testing zooming.
added multiply methods
minor debug comment
commenting and added enable for upward dirty sets.

Upward dirty flag setting is now disabled by default.
added missing group behavior initialize.
added ZoomGroup usage instead of GroupNode
Finished and cleaned up code.