Move code for block rotation out of BlockSign (also used for Skulls and Banners)
Fix GlowEntity.getFacing() being opposite of actual facing. Change Position to start at North, and update BlockSign to match. Remove derpy math in facing logic.
Javadoc fixes and math fix
Merge branch 'facing' into skulls
Move code for block rotation out of BlockSign (also used for Skulls and Banners)
Merge branch 'facing' into skulls

Conflicts:
	src/main/java/net/glowstone/util/Position.java
Update Skulls to use Position.getDirection() and GlowEntity.getFacing()