This is used to determine the bounding box for interaction in the client
(the ray that's cast from your camera interacts with it to determine the
highlighted block).
TODO: Make it work better with metadata.
This commit also fixes one of the issues with snow: ref #194
This also fixes a bug where a chest, when removed and replaced, would
have the same inventory. Also adds validation on update sign packets to
make sure it is indeed a sign they are updating.