Support for chunk based loading

[HeadClot]

This is an optimization technique used in games such as Mine Craft and other block based voxel games.
You can watch a video on it here by Jens Bergensten at DreamHack 2011. Without chunks voxel games depending on the size of the world may slow down significantly.

The general Idea is that the game world is broken up into vertical parts called chunks. You can read up on it here