Created functions to trivially translate an ID to a Behavior and vice
versa. Sent ID over packets instead of Behavior pointer. This should
allow Linux and Windows to play together.
Added Luigi model.
Renamed all previous references to 'Luigi' to 'Mario2' since player 1
isn't always mario, and player 2 isn't always luigi.
Now server is always mario and client is always Luigi.
Luigi model credits:
Original model by Cjes, converted by AloXado320, textures added/fixed by
SunlitSpace542.