Added box and physics components

Box is sort of part of the CLD-Util suite; it simply stores a Box
object. Physics is used by the PhysicsEngine system for moving
things around and checking for collisions.
Added a check for Box component

Box is used for sprites, makes things easier to draw.
Created PhysicsEngine system.

PhysicsEngine handles all the moving entities, collision detection,
etc. Should be fun/scary to write