Fixed collision detection issues

There was a problem where you would "stick" to the wall due to
the collision system thinking that you were standing on top of
tiles when falling down while moving into a wall. Should correctly
handle this case as well as any others now, though I think there
are still some corner cases that we should never run into as long
as we stick to tiles.

The camera system should also work better, with square objects
actually being square now due to having the correct aspect ratio.