HUD Fixed, Sound Done, Bug Fixes, Added Features

Set up the HUD to properly get and use the various objects and data.
Implemented most sounds. Expanded the level so you can't see the
infinite blue void. Gave the mechanic actual legs. Car now kills zombies
on impact. Zombies can now kill the car. If car dies, the player now
loses. Added arrow to indicate level exit once in the car. I probably
did some other stuff that I've already forgotten too.