Saving image to disk

Can now save a generated heightmap as an image to the disk. Also tried
to better understand the PerlinGenerator
Merging track, if we wait it'll be hard to merge due to some problems in later commits
Huge commit, cleaned up in Game1.

Cleaned up Game1 to make it more extandable.
Car-rendering moved.
The car wheel spins coorectly when in reverse:)