Beta Half Pipe 2.1

Added loop de loop, tunnel, and skate park models to the level. Also rebuilt and improved the half pipe.

The trick to landing the half pipe is to pull the hand brake and steer right or left 2 or 3 blocks from the top of the ramp; this will spin the car around so it lands forwards. Timing the maneuver is the key to sticking the landing, it should land smoothly. A game pad works better than a wheel. The best cars for jumping seem to be ones witrh any suspension type other than race, and cars...