Skulls [WIP]

This implements Skull rotation, naming, and type mechanism. I've done my best to get most of the code sorted, however I was unable to work out why the client isn't receiving packets that update the tile entity.

There's still some things that need to be implemented/fixed, such as a couple NPE's, changing to use PlayerProfiles (to be more in line with vanilla), and implementing the textures part of the NBT.  I may also need to document a bit more.