gamemath.py: cleaned up move_toward_wrap

Made it way better/cleaner/shorter/faster?

By the way, turns out I don't understand math anymore. `delta1` and
`delta2` always ended up being additive opposites, and because of how
I did the comparison, it ALWAYS ended up picking delta2. THAT'S why
I had to do `value - copysign(rate, delta)`.

By by the way way, I STILL don't really understand what's going on
or how this is actually working. Ughhhh I'm getting stupider