Redraw modified objects only. This change is the initial implementation of using dirty region to avoid redrawing unmodified DisplayNode objects, i.e. DisplayNode objects which have setPosition() or setScale() called by an application. This code enables only when Layer.USE_NEW_RENDERER is true.
Merge pull request #4 from tkihira/hbono/use-dirty-region

Redraw modified objects only. This change is the initial implementation ...