TiledMap Update
- BackgroundMap has been deleted in favor of TiledMap. TiledMap
  uses the bridge pattern to separate implementation from the
  interface. This change allows for subclassing TiledMap to extend
  functionality. Previously, extension was done through composition
  and delegation, but this could have been a maintenance hazard
  were the original class ever to be modified.
- This change renders many classes in this snapshot obsolete,
  including DoodadMap and BackgroundMapFactory.
- TiledMap does not strictly depend on Background, allowing for
  custom backgrounds in the future.
- TiledMap and CoordConverter consider size as a long type. This
  allows height and width to be their appropriate maximum
  capacities without penalty.