encoder: protect public APIs against NULL pointer arguments
testbench: Added stress test cases for chroma_pp, chroma_ps and chroma_hps filter functions
asm: Optimizations and cleaups on ipfilter functions
testbench: Added stress test cases for check_IPFilterLuma_ps_primitive, check_IPFilterLuma_hps_primitive and check_IPFilterLumaHV_primitive filter functions
asm : Optimisations in blockcopy_sp asm routines(2x4, 2x8, 6x8)
rc: Don't do resetABR in CRF.
vbv: set vbvminrate
asm: fix bug in cvt16to32_shl
slicetype: cast mvmin/mvmax indices to signed 16bit values
weightp: clip lowres MV before using for motion compensation

Even the lowres MVs with very restricted merange can go beyond the available
pixels.  This was causing memory access exceptions on some clips.
cmake: a few fixes for building on ARM (Rapsbery Pi in particular)

Next step will be bringing over ARM cpu detect assembly functions:
  x265_cpu_neon_test()
  x265_cpu_fast_neon_mrc_test()
api: mark externed variables for import from Windows shared library
api: we don't need stuttering header guards
weightp: fix hash mismatch

all references should have same luma and chroma denominator
ratecontrol: to set B-ref frame QP as Lower then B-Frame QP for RC with CQP mode
asm: 16bpp asm code for intra_pred_ang8 - all modes
Test bench : Stress test cases for remaining filter functions.
asm : Clean up and minor modifications in pixel_sub_ps asm functions(2x4, 2x8, 6x8)
asm-16bpp: assembly code for IntraAng32x32 all modes

--HG--
extra : rebase_source : 9bb46e8a26667d0945d443480a4ba2f9d0a8aa18