An attempt to correct what went horribly wrong with Grumper.

Main changes:

- Movement physics have been revamped to now have near-instant acceleration and deceleration both on land and in the air (though it's _slightly_ lower in the air still), as well as decrease max horizontal speed.
- Levels were tweaked a bit to accommodate the physics changes.
- The removal of selectable difficulty. This caused the experiment to break because everyone selected a different difficulty.
- A fix for the death location decals not actually getting limited to 100 on-screen.
- When you quit the game during a level, it still saves your death locations for that level.

Again, attach your stats-xx.txt file here when you're done playing.