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
sao: nit
sao: remove unused m_qp member
fix lossless
sao: nits
rc: write I/i slice in stats file based on whether openGop is enabled or not.
rc: don't read slicetypes from qpfile in 2nd pass.

slicetype has to be taken from the stats file from prev pass.
Merge with stable
replace g_rasterToPelX[g_zscanToRaster[idx]] by g_zscanToPelX[idx]