slicetype: Bidir cost estimation added to lookahead
primitives: added C primitives to compute SSIM
calculate SSIM for each Row after deblock, sao
Update testbench for threadpool
TComSlice: Removed un-used createExplicitReferencePictureSetFromReference() Method
tcomslice: removed un-used checkThatAllRefPicsAreAvailable() function
tcomslice: removed un-used sortPicList() function
pixel8.inc: replace calcRecons4 vector class function with intrinsic.
pixel8.inc: replace calcRecons8 vector class function with intrinsic.
pixel8.inc: replace calcRecons vector class function with intrinsic.
pixel: replace getResidual16 from vector class to intrinsic
pixel: replace getResidual32 from vector class to intrinsic
pixel: replace getResidual64 from vector class to intrinsic
piclist: add class PicList for picture list manipulations

Created new file piclist.cpp and piclist.h for linked list manipulation, there
will be no intermediate storage in piclist, PicList just links TComPic objects
together.

PicList will be used to replace TComList<TComPic> and this will remove std::list
dependency in x265
piclist: pass non-optional pictures by reference to avoid NULL checks
Use unweighted pixels before interpolation for Luma in Motion Compensation
Fix for possible memory access violation in applyWeight()
Check against numRows in applyweight

applyWeight() processes rows a 'refLag' number of rows in advance as compared to
the current iteration in compressCTURows()