Rotaters, Crates, and Fast Conveyors

Added a few new features and minor tweaks:

• Added a message if the game thinks you can win this turn.  Its only as intelligent as the AI opponents, so if there is a crate or robot in the way it won't take that into account.
• Added fast conveyors that move at double speed.
• Added rotaters, which turn the robot without moving it.
• Added crates, which block movement but can be pushed around.

There is one known issue that the crates make obvious - if you have multiple robots or crates in a row on a line of conveyors, it will sometimes move the object in the back before the object in the front, pushing all the objects in front of it.  That is probably the next thing I'll work on fixing.