cleanup vestigal voxel world stuff (or move it to another repo)

[collinalexbell]

HackMatrix started going down the path of being a minecraft like voxel engine. There is a lot of vestigal code in world.cpp for this purpose that should be deleted or moved to another repository. There is also stuff in that file that is currently being used (namely everything in systems namespace... and a few action functions), so that will need to be disentangled.