"memdbg" fixes for a bunch of OpenCL formats. See #739.

The #include "memdbg.h" must basically be the last included header.
MEM_FREE bugfix for rar5-opencl. A buffer was freed in done()
but should be freed in release_clobj()! See #739
Add some missing inclusions of memdbg header. See #739
Do a sane job during OpenCL initialization.
Optimization for NVIDIA SM 30 and beyond . Gives 2000 c/s on GTX Titan.
- For future usage.