Local multiplayer & more (V3.0)

I did a complete overhaul of the way that the game processed inputs, allowing for local multiplayer across two (or more) gamepads.

Sadly this does mean that the camera will no longer swivel to look at the bot when you are driving.

Players will now spawn at the center of the field. You can spawn as many players as you have gamepads, theoretically, there is no limit.

I'm going to add a menu shortly, as the way that currently exists to change fields is annoying and unsustainable.