Some formatting done to DisplayObject2D.
Improved readability of DisplayObjectContainer2D.
Optimized Sprite2D.
Improved Image2D class.
Optimized Quad2D class.
Removed the native overlay code from Render2d because native display
objects should be managed by Tetragon's Screen class.
commented out render2d stats display code.
Added ClippedSprite2D class.
Implemented View2D class as a clipable root view for Render2D.
Added benchmartk test.