A rough octree implementation to support frustum culling and raycasts in complex THREE.js scenes.

NOTE: Code is generally unmatained and unfinished.

• Max depth is needed in case there are a bunch of objects right on top of eachother
• Consider adding an optimization using SAH and constricting the bounding boxes a a bit more
• Provide an option for iteratively flushing all pending inserts because this can be expensive on cast operations
• Raycasts can be a bit slow when the tree is large. This seems due to a lot of objects not being pushed down into leaves that are straddling an octant boundary.
• Add, update, and remove operations are all delayed at the moment as well as the objects being pushed down into the tree -- we shouldn't need both (or either? Remove them?)
• Optimize object removal.
• Use something like an SAH algorithm to decide when to split.
• Shrink the bounds to a size that optimially constrains the child objects?