Implemented item frames, a part of #689

+ Implemented Item Frames
* Fixed Pitch and Yaw being wrongly flipped in the protocol (XOFT!)
Used new BLOCK_FACE constants

Also added more comments
Added an explanatory comment
Added a brace

====
{       }
{  __  }
{  | |  }
====

REMOVE ALL THE BRACES!!
Merge branch 'itemframes' of https://github.com/mc-server/MCServer into itemframes
Changed BlockFace type to eBlockFace
Fixed possible ASSERT failure
De-breaked stuff
Merge branch 'itemframes' of https://github.com/mc-server/MCServer into itemframes
Merge branch 'master' into itemframes

Conflicts:
	src/Entities/Entity.h
	src/WorldStorage/NBTChunkSerializer.cpp
Merge pull request #694 from mc-server/itemframes

Implemented item frames, a part of #689