Adding hatchback car.

Just a few changes to add a hatchback car and a new hatch part (like a door, but with storage). Give me your thoughts. Not if people think we need another car. But it would be nice to have a separate option to the beetle for a small but enclosed car. I based it off from the Mini Cooper, which is why it has dual fuel tanks.

Also, I totally need to make a program to write these vehicle JSON for me.