[UNSTABLE] Physics Reconstruction

In this update I've taken the time to kind of clean up the physics
again. They are still junk.. which I'm not too happy about, but other
methods aren't working. Trying to figure out a way to possibly implement
SAT collision response style.

This update also fixed a lot of rotten inneficient code that was in the
World class; the application can now run 8,000 entities - physics and
all - rather than just a measly 100. We'll see what else I can do to the
physics to get it just right.