Deletes old test game
Demo game is now playable
Updates demo game with steering and changes in sprites
Fixes smaller bugs in sprites
Refactor class names in game demo
Strips Box2D from game
Fixes ordering in game node
Adds frameRate property to SpriteBox and improves update methods.
Fixes node to box transformations for hit tests
Fixes minor code issues
R=abarth@chromium.org
Review URL: https://codereview.chromium.org/1179333002.
Sprite nodes use Point instead of Vector2
Updates sprite test app
Refactors accounting for pivot points in sprites
Adds abstract NodeWithSize class in Sprites.
Refactors SpriteNode to Sprite
Refactors TransformNode to Node (may need to find another name as it conflicts with Sky's Node).
Sprite system now uses and caches transformation matrices.
R=abarth@chromium.org
Review URL: https://codereview.chromium.org/1180703002.
