* EndGameState.cs:
  Initial early version.

* Game.cs:
  Revamped state system.
  Cleanup.

* GameTime.cs, Button.cs, ArgParser.cs, MenuState.cs, BlockSpawner.cs:
  Cleanup.

* AState.cs:
  Added automatic key press handling.

* Player.cs:
  Added OnCollision event.
  Cleanup.

* GameState.cs:
  Added start / end events.
  Pressing escape will now take you to the menu.
  Cleanup.
Merge commit '6ffd318325d41c8d25a6099873db6c6cdb23edc0'