Merge changes I359aa49c,Ic8ca5afb into nextgenv2

* changes:
  Generalize txfm scale in highbd quantizer
  Parameterize transform scale for quantizer

diff --cc vp10/decoder/detokenize.c
Simple merge

diff --cc vp10/encoder/encodemb.c
Simple merge

diff --cc vp10/encoder/rdopt.c
Simple merge