Naive first implementation of new dirty rectangle tracking
Fix logic error with stale rects
functionally complete dirty_rect rewrite
factor out a rectangle manager
Change name of newrect to currentrect
Remove cruft from old code
Remove cruft from canvas.js
Improve docs a bit
Add debug mode, and fix error in merge code
Rename merge->mergeSet and simplify so that it works in place.
Optimize order in which entities are drawn
Optimize mergeset algo
Remove extraneous flag and console debug
Merge branch 'dirty_develop' of https://github.com/starwed/Crafty into starwed-dirty_develop

Conflicts:
	src/canvas.js