WIP - refactoring lane change code
Refactors code to make it a lot more readable. The state of it:
* Driving north and changing lanes from LEFT to RIGHT works.
* Driving north and changing lanes from RIGHT to LEFT works.
* Driving north and changing lanes from LEFT to WALL results in changing into the RIGHT lane.
* Driving north and changing lanes from RIGHT to WALL works (i.e it doesn't let you)
* Driving south still has some issues
* Driving east/west still has some issues