- Some comments in hip_hcc.cpp
- document hipHostRegister* flags.
- expand docs on hipHostRegister/Unregister. Use "register" rather than
"pin" to describe action these take.
- change required CUDA version to 6 (require unified memory)
- remake doxygen.
changed Cuda to CUDA for consistency
changed NVIDIA to Nvidia for consistency
corrected apostrophes
corrected section "What hardware does HIP support?"