sao: simplify entropy coder initialization [CHANGES OUTPUTS]

Remove the hack from the HM that preserves fract_bits from the first row to all
rows; it never made any sense and we don't pretend to be anywhere near close to
bit accurate with the HM anymore.

This commit removes the Entrppy coder in FrameFilter since it was only used by
SAO and moves it into the SAO class.  The startSaoEnc() method is removed
entirely and another call to resetEntropy() (an expensive method) is replaced
with a load of the frame encoder's m_initSliceContext

--HG--
extra : rebase_source : 230ce0ee1707f574231465991ff6bfa9563b7db1
sao: nit

--HG--
extra : rebase_source : 63077f0e325f7cf39e90080919fda2a8cfd8b5a8
sao: remove unused m_qp member
fix lossless

--HG--
branch : stable
sao: nits
rc: write I/i slice in stats file based on whether openGop is enabled or not.

--HG--
branch : stable
rc: don't read slicetypes from qpfile in 2nd pass.

slicetype has to be taken from the stats file from prev pass.

--HG--
branch : stable
Merge with stable
replace g_rasterToPelX[g_zscanToRaster[idx]] by g_zscanToPelX[idx]