Update v1.3

For the time being, this will be the final update. It brings the following changes:

Added

• Two new tracks have been added

Changed

• The race track generator now produces more organic race tracks.
• The color scheme is now more vibrant, as gamma correction has been fixed
• Tracks now have a definition file
• The racers have been nerved: They now have a really high max speed, but can only accelerate with one tile per step.