primitives: fix ordering of LUMA_4x16 LUMA_16x4 to match other AMP partitions

This also fixes the testbench to properly represent 16x4 and 4x16 partition
primitives
encoder: prevent divide by zero in elapsedVideoTime calculation
rc: improvements for ABR

1. modify rateTolerance from 0.1 to 1.0, in order to allow the final bitrate to
fluctuate more(CBR to ABR)

2. ncu in initialization of ratecontrol is set according to 16x16 block size
which is same to x264, for the empirical formula in x264 is for 16x16 size.

3. do more modification to make ratecontrol algorithm of x265 more similar to
x264 for x264 has been developed for about 10 years and is very mature , it is
reasonale to take its method firstly.
Added tag 0.5 for changeset 69acb3cb777f
Merge with stable
no-rdo: add no-residue candidate in merge2Nx2N
asm: assembly code for pixel_sad_16x4
asm: improvement on chroma_hpp{2,4} by reduce memory operator
asm: declare asm function pointers for sad_32xN partitions
no_rdo: implementation of new early exit

early exit is done when the RD cost of best mode at depth "n" is less than the
average of RD cost of the CU's at depth "n" of previosuly coded CU's(CUAbove,
CUAboveRight, CUAoveLeft, CULeft, CUColocated).
For HD videos
performance improvement of 20 to 27%
bitrate increases by 0.75 to 0.02%
Cleanups: MVField - make members public.

set and clear methods take many cycles, where most of the time only one index need to be set. By giving public access, caller can set required indexes.
Cleanups: Remove call to setALLMVField, and set only required members.
cleanups: Remove unnecessary reset.

If refIdx is set to NOT_VALID, mv will not be used. Hence resetting MVs to 0 can be safely removed.
TComDataCU: Remove initializations in initCU() already initialized in create()

currently m_partSizes, m_mvpIdx[0] and m_mvpIdx[1] all three variables
initialized using memset in TComDataCU::create() and same initialization in
done in TComDataCU::initCU(), removed the memset in initCU() to avoid the
duplicate initilization
Merge