Revert "Removed ATOMIC_COUNTER_BUFFERS entirely"

This reverts commit 46be53c8883dc7fff25e7abe2f60d76220b3056d.

Conflicts:
	src/clvoxel.c
Added link to *why* OSX is not supported.
Nvidia-NVML support for GPU temperature query
NVML stuff put into its own file
Removed overlapping text
AMD gpu's should display temp via Overdrive5/6
Fixed(?) neighbour copy graphic glitches
Removed OpenCL kernel