Added coarse collision detection structure

---Updated Vect3 class ever so slightly for minor speed optimization
---Added BVTNode class - this is a node in a bounding volume hierarchy
tree, used for coarse collision detection. TODO: Construct, destruct,
insert, remove methods for tree.
---Added BoundingSphere class: Will be expanded to a BoundingVolume
getup... somehow... basically contains information for a sphere in 3D
coordinates, and methods for if it's colliding with another sphere or
point.