added methods that can reset the game.

doesn't work yet, but committed non the less.
Moved some code, and made some process on restarting

TODO:
- despawn car bodies during restarting (we now have ghost cars)
- make all clients restart instead of server only (easy)
Altered Collision detector to comply with restart mechanism

Local restarting seems succesfull now, focus should now be to have
network wide restarts.
Completed restartable implementation!!

The game will now show the game results for 20 seconds and will then
restart. Tested as far as possible. Also contains some bugfixes. I want
to test this with 4 devices and if all goes well I'll merge with master.