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
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
Blocklight and skylight now compressed
Attempt to fix errors
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
Implemented suggestions
Another small speed improvement?
Fixed indent
Implemented comments
Merge pull request #863 from mc-server/chunkysparsing

Chunky sparsing