10x speed optimization

Threading was already written into the game, but was still prone to some issues. Today I updated the game with with one that uses up to 8 threads, so it is many times faster. There is also a smaller improvement from simplifying some math equations in some places.

Additionally, in this update I  fixed a bug that was allowing joints to constantly rotate, which led to animals with spinning propellers. That's dumb. I also added a greater likelihood of fine neural adjustments.

And, I changed the Rule. The previous Rule was that there were a few segment types that could defeat each other in a scissors-paper-rock fashion. It made good content because it caused the animals to become more elaborate.

However the new rule is that an animal beats another if it hits it with a mouth segment at a very straight-on angle.
This has the weird side-effect of causing flocks of animals that fly straight across the screen, but it promotes vision-based steering behaviors early in the game.