Removed TileType and added OnLeaved and OnArrived to BaseTile

Signed-off-by: Kalle Sjöström <c06ksm@gmail.com>
Added a simple teleport floor tile.

It selects a random tile in its OnArrived and sends the avatar there.

Signed-off-by: Kalle Sjöström <c06ksm@gmail.com>