Optimized chunk loader
Better StreamNextChunk() method
Merge branch 'master' into ChunkLoader
Stream 4 chunks per tick. Added priority.
Added distance check.
Merge branch 'master' into ChunkLoader

Conflicts:
	src/ClientHandle.cpp
New c++11 stuff.
Use two lists and 2 chunk send prioritys.
Fixed submodule downgrades
Reverted plugin remove
style.
Merge branch 'master' into ChunkLoader

Conflicts:
	src/World.h
Merge branch 'master' into ChunkLoader

Conflicts:
	src/ChunkSender.cpp
	src/ClientHandle.cpp
	src/World.h
Use 3 priorities.
Merge pull request #1500 from mc-server/ChunkLoader

Optimized chunk loader