Add boundary box/circle around player

[nulltone]

Need to add a boundary box/circle around player so it doesn't overlap with collidable tiles.

[cantsin]

Maybe come up with a generic library/aabb.lua (axis aligned bounding box) file that we can use for moveable sprites? Ideally the aabb would fit the image as tightly as possible, and there would be functions to e.g., quickly determine if two aabbs overlap (the math is simple).