Garage improvements

[img=https://s3-eu-west-1.amazonaws.com/hplovecar/house04_sm1.gif][/img] Changelog: - added roads leading to houses, making them easier to find and easier to drive into - added garage-car impact sounds - added sounds and a particle effect for garage door's destruction - car engine sound is now muffled indoors - car is now slightly visible when indoors - houses shouldn't overlap anymore