Remove PlayerIndex references, as PlayerIndex.One is always assumed.
Move SpriteBatchExtensions to its own file.
Move the VirtualController creation from ScreenRenderer up to PuzzlePathGame.
Add level 9.

This will probably be level 3 in the final version.
Add level 10.
Add level 11.
Created Pages in the Level Select Screen and Updated How to Play Screen

These two additions have been created and tested, but further testing
may need to be done.
Add level 12.

This will probably be moved earlier. This level will seem familar to
those that have tested this game a lot :)
Delete the test level.
Add level 13.
Add level 14.
Major overhaul of the input subsystem. The design is weak right now, but it lays some important groundwork.
Refactor the ScreenRenderer and Scene so that Scene is more of a "dumb model".
Rename ScreenRenderer to RenderComponent.
Improve input infrastructure in GameScreen.
Move TopLevelModel to its own file.
[Bugfix] LevelSelectScreen adds a new MainMenuScreen rather than returning to the old one.
Make the TopLevelModel controller ~not~ a WritableVirtualController.
Simplify input usage from GameScreen subclasses
Make sure that no screen is removed without calling ExitScreen() on it.