Commit is being made to allow additions of GPL3+ code previously
un-addable. With these changes, contributions back to cuberite are
possible with the backporting exemtion, as well as adding stuff in
minetest with minetest code properly being read through and implimented
to upgrade it to GPL3 from GPL2.
project still has Apache2.0 license and credits to all its contributers, but now has the freedom of GPL3+ and all the code that can be implimented and shared with it.
Closes#1244
Initially I was just going to add the cChunkData to cSetChunkData but profiling revealed
that the copying wasn't even the biggest slowdown. Much more time was being spent in
cChunk::CreateBlockEntities and cChunk::WakeUpSimulators than was in memcpy so I've made
those significantly faster as well.
Optimisations performed:
* cSetChunkData now stores blocks in a cChunkData object
* cChunkData objects can now perform moves even if they are using different pools
* cChunk::CreateBlockEntities now iterates in the correct order and only over present chunk sections
* Similarly for cChunk::WakeUpSimulators
* cSetChunkData::CalculateHeightMap now shortcuts to the highest present chunk section before checking blocks directly
