Engine:
Added (R)ender, Z to toggle frame-limit, X to enable/disable center gravity.
Changed from 3 to 5 robots.
Tweaked robot/ball scales to be accurate to the actual game.
Made collisions more accurate.
Tweaked acceleration/speed/friction values, to be accurate to the actual game.

Behaviors:
  Behavior Engine:
    Added brain swapping between robots, allowing two robots to exchange behaviors if they'd rather be in the other robots place.
  Added:
    ballUnstuck - Spins when near the ball, if it hasn't moved in a while
    robotUnstuck - reverses when robot hasn't moved in a while, but it has been trying to.
  Modified:
    All other behaviors, to adjust to the new scale/speed values.