v1.2 ghost racing

This update adds the ability to save your PB as a ghost when you finish the game so that you can play against it later. The file is saved with the filename "pb.rec" and you can delete it if you don't want to play against yourself.

A couple of minor bugs were also fixed, most notably an iffy spot in the level where you could quite easily get stuck, as well as properly resetting the body when you press "R".

Although the arms now render as rectangles instead of pure lines, there are no functional changes (i.e. all physics are the same as in v1.0 that was released for the jam).