This is a rather larger commit than I'm happy with, but oh well.
This kills off the enormously overcomplicated BlockIterator and replaces it with a VoxelRayTrace class containing ray tracing generator functions. These functions are independent of any Level. They yield Vector3 objects with current ray trace positions to allow implementations to handle the intercepted blocks in their own ways.
Living->getLineOfSight() now uses VoxelRayTrace instead of BlockIterator.
