Revision D7.4 (Simple World Treadmill)

Changed Class:
- World

World now has very simple test methods for adding additional instances
to the left, right, up, and down - while maintaining only four instances
at any given time.

TODO:
- Test shifting entire world back to origin along with player.
- Create algorithm to properly offset instances that pass the maximum
float values for their children.
- When all entities shifted to origin, create algorithm to properly
handle new instance offsets so they don't continue from where we were,
but to where we moved.