Sort of implementation of chunk sparsing

Issues:
* Chunks are flipped
* Slow/inefficient/badly coded
* Only blocktypes are 'compressed'
Performance improvements and chunk flipping fixed
Fixed some bugs

* Fixed undefined behaviour
* Fixed compression failure
Merge remote-tracking branch 'origin/master' into chunkysparsing
Grass now grows under up-side-down slabs
Remove old function
Merge branch 'master' into Slabs

Conflicts:
	src/Blocks/BlockDirt.h
Speed and memory improvements

* Changed array to be continuous, so no more layer splitting
Nibbletypes are compressed

+ Added nibble compression
* Fixed an off by one
Add CanChangeDirtToGrass function to Block Handlers.
Merge branch 'master' into Slabs
Remove old import
Blocklight and skylight now compressed
Attempt to fix errors
Statistic/Achievement defs
Maybe speed improvements?

* Use a single index to determine from when to begin copying data
* Use heightmap to determine first nonair block
Replaced all the .data() calls so the code compiles in VS2008
Small changes
Some change to Entity.cpp

* Added comments to BroadcastMovementUpdate() and the collision tracer
Merge branch 'master' into fixes

Conflicts:
	src/World.h