[CIT-38] > feature/vehicles

Cars are appearing on the roads and are moving between the citizens workplace and residence. The number of cars is limited to the number of residential zones. A basic collision detection system is implmeneted which enables only car in an intersection. Multiple connecting intersections count as one, so more intersection next to each other could cause traffic jams. To maintain the continuity of the traffic, if a car wasn't moved in 20 sec, it disappears.