fix chroma distortion for 4:2:2
analysis: comments
rc: fix chroma qp and chroma lambda derivations.

fix the chroma qp values for Main10 profile, derive chroma qp from luma qp values
according to the HEVC spec.
improves quality at high qps.
rc : fix bug in deciding qp for first frame in CRF
cmake: do not use a cache string for version found in hg_archive.txt (refs #84)

This was not passing the tagged version number to version.cpp