Adds backward adaptation and differential forward updates of switchable
interpolation filter probabilities. Also adds some cosmetic cleanups
and minor fixes on mv_ref probabilities.

derfraw300: +0.353% (with most coming from switchable interp changes)

Change-Id: Ie2718be73528c945fd0d80cfd63ca2d9cb3032de

This commit makes operations of the superblock intra coding rate
distortion optimization consistent with those used in the encoding
process. Given the test prediction mode and transform size, the rd
optimizer encodes and reconstructs each transformed block of the
superblock consecutively, then computes the total rate-distortion
costs accosicated with the current superblock to select the coding
decisions.

It achieves coding performance gains:
derf 0.353%
yt   1.111%

Change-Id: I0da2eb7a71361dfb8c1384927fc536b0c2790d07

in the calculation of maximum number of tiles in log2 scale.

Change-Id: Id283d6e51a8b926015fd3fc631cdbfb4b8268d4a

Overall PSNR drop on derf set is -0.024.

Change-Id: I1c05d2ace83488205ca16e3b06cd5f0ebceec8d6

Enable iterative motion search for compound inter-inter prediction
of block sizes 4x4/4x8/8x4 only when best coding quality is selected.
The iterative motion search provides about 0.1% gains for derf and
stdhd at this point, at the expense of longer runtime.

Change-Id: Idc03e7f827e51f1bb8d269bc3752ee297a6bbfe5

Change-Id: Ib557cc6351404b9e178e95a545883eb3666f11f0

Migrates costing changes/fixes from the rebalance expt to the head
without the expt on.

Rebased.

Change-Id: I51677d62f77ed08aca8d21a4c9a13103eb8de93f
Results:
derfraw300: +0.126%

Moving some code from vp9_pack_bitstream to encode_txfm function.

Change-Id: Icc25d6083e54f09886216fea632ceac002042d7f

Change-Id: Ie869ea4992e26867caec46cb878fc86a646aeb9f

Change-Id: I02c17fb733c0f3c22dc3167c3d3182797415f1ae

Change-Id: I615125483da71a623a930d6e20c42df82ea0e6ee

Change-Id: I2dfc569106b29fbe4da20585a0e85e5e9ea6a4db

Restrict get_matching_candidate() to considering
mvs at 8x8 and larger sizes for last frame case.

This is to reduce the HW load of using vectors down
to the 4x4 level from the previous frame.

Change-Id: I6505e610fd63a4e22d67f136aec7905a01b893ba

speed >1 can be spead up by turning these on - lost in a prior commit

Change-Id: Iaef85e10ecfeec3aea5ab0e691edf02bb7f5190d

Change-Id: Ibaa47be878c1cd84d88d7518418d2d8d38224e70

And removed 1st pass specific version of intra coding funcitons

Change-Id: Ia54e67c71d750957cb2efda8360bf2133468498a

Change-Id: Ieb4a8c97bf1b1dfb993f40a9a3ef3bed5ae7d948

This speed 1 - uses variance threshold stolen from static-thresh
to determine split.  Any superblock with greater than the variance
set by static thresh * quantizer index squared is split. In addition
transform size is set to largest size less than or equal to partition
size, sub pixel filter is set to normal,  and only 12 modes are used
at all.

Change-Id: If7a2858ee70f96d1eb989c04fd87a332b147abef

* changes:
  Remove i4x4_pred.
  Remove unused table.