Construct paths relative to the Cuberite sources with PROJECT_SOURCE_DIR, instead of wherever the first CMakeLists.txt file happened to be with CMAKE_SOURCE_DIR.
In Android's case, the latter was in a folder called android/ but that's not the root of the source tree, so any file path built off that root was wrong. This caused file-specific warnings exclusions to fail to apply.
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
* Replaces AppendVPrintf with fmt::sprintf
* fmt::ArgList now used as a type safe alternative to varargs.
* Removed SIZE_T_FMT compatibility macros. fmt::sprintf is fully portable and supports %zu.
* Adds FLOG functions to log with fmt's native formatting style.
