Awesome Speed Gains!

I completed my updates to broad-phase collision and the SpatialGrid.  In addition, I removed the "spatial" package and put the classes in the "collision.broadphase" package.  The speed gains are very noticeable on Firefox 3.6!  Overall, I was able to cut down processing time by doing the PCL caching and sharing, plus I modified R.struct.Container and added a new append() method.  This method appends one container to another by chaining the head of the second container to the tail of the first.  It's a destructive method, but useful in this situation, and it's a big speed improvement.  Additionally, I was able to drop two loops from the PCL construction method which sped things up even more.