Tile system is now set up so that instances have a reference back to their tile. This is required for use with the hash grid because it is the instances that get hashed, not the tiles... so in order to draw a (hashed) list of instances they have to know how to draw themselves!
Added TODO comment. Now that some of the systems are starting to come online with higher-end features (such as the Tile system and it's hash grid) we need to setup the pool module to have customizable pool sizes per pool.
Tile Module changes

Beginning work on the next major upgrade to the rendering systems: the
Tile module will soon support visibility testing via a hash grid.