Clean up bouncy fof code + fix bugs (closes #291)

I cleaned up the terrible bouncy FOF code and fixed the bugs mentioned in #291 (closed).
Also fixes a bug where the bounce strength was dependent on your skin's height. Short characters could get softlocked while Fang goes to space.

Minor gameplay change: Bouncy FOFs no longer forcibly unspin you, but you'll regain full control when bouncing vertically.

7/22/2021 text exe: srb2bouncy.exe