BoardTileCollection now implements ICollection.

git-tfs-id: [https://tfs.codeplex.com:443/tfs/TFS15]$/Atomix;C39424
Update levels.

git-tfs-id: [https://tfs.codeplex.com:443/tfs/TFS15]$/Atomix;C39425
Move CanGo* methods from collection to Level.

git-tfs-id: [https://tfs.codeplex.com:443/tfs/TFS15]$/Atomix;C39426
LevelGenerator: Loading existing xnb levels.

git-tfs-id: [https://tfs.codeplex.com:443/tfs/TFS15]$/Atomix;C39427
LevelGenerator: Loading from XML too.

git-tfs-id: [https://tfs.codeplex.com:443/tfs/TFS15]$/Atomix;C39428
LevelGenerator: Handle is not needed as we do not work with textures.

git-tfs-id: [https://tfs.codeplex.com:443/tfs/TFS15]$/Atomix;C39429
LevelGenerator: Load level button.

git-tfs-id: [https://tfs.codeplex.com:443/tfs/TFS15]$/Atomix;C39430
Logic: Change field to properties (WPF Binding).

git-tfs-id: [https://tfs.codeplex.com:443/tfs/TFS15]$/Atomix;C39431
LevelGenerator: Binding Board.

git-tfs-id: [https://tfs.codeplex.com:443/tfs/TFS15]$/Atomix;C39432