added prefetch instruction
Merge branch 'hevc' of https://github.com/OpenHEVC/openHEVC.git into hevc
removed all XPEL_W functions
added small optimisation in EPEL_V_compute
changed some unpacklo to cvtepi
added more cvtepi to replace unpack + srai
change _mm_cvtepi8_epi16 into _mm_cvtepu8_epi16
new optimized version of QPEL_V
Merge branch 'hevc2' into hevc

Conflicts:
	libavcodec/hevc.c
	libavcodec/hevcdsp.c
	libavcodec/hevcdsp.h
	libavcodec/hevcdsp_template.c
	libavcodec/x86/hevc_mc_sse.c
	libavcodec/x86/hevcdsp.h
	libavcodec/x86/hevcdsp_init.c
remove useless include
improve gitignore.
Install new include files.
start cleaning CMakeLists.txt
(gitignore) Add rules and comments
(cmake) Common Yasm arguments moved to a variable
(cmake) Eliminate redundant information in flags passed to compiler

CMAKE_C_FLAGS is a variable (empty by default) used by cmake to
configure command lines. Is is not necessary to set all _DEBUG,
_RELEASE, etc. variables to configure flags.

See http://www.cmake.org/Wiki/CMake_Useful_Variables#Compilers_and_Tools
for more information
(cmake) Minor fixes
(cmake) Less code to build hevc / hevc_sdl2
(cmake) Refactoring on wrapper_hm/CMakeLists.txt
(cmake) Enclose some path variables with double quotes.

This avoid problems if some paths contains space characters.
fix OpenHEVC/openHEVC#15
If some paths still needs to be fixed, please re-open OpenHEVC/openHEVC#15