Started fixing Function argument performance bug

Because there are so many different function constructors (Floor,
Player, Goomba, etc.), Chrome kept re-optimizing the tryCollision
function for hit_check, thing, and other to be different. thing and
other both inherit from Thing but JavaScript performance optimizations
don't respect prototypal inheritance. Agh!

More fixes will need to be done to fix ThingHittr.checkHitsOf*, probably
involving function generators so separate functions can be optimized
separately.