Changes to calculation of sr_coded_error to include 0,0 case.
Experimental use of sr_coded_error in calculating correction factor
for estimating the allowable Q range.
Reinstated some code needed for calculating section_intra_rating.
Add flash detection in calculation of KF boost
Increased tolerance in testing candidate key frames (needed with
longer motion search as this tends to slightly increase inter %.
Zbin changes for 8x8.
Other minor adjustments, refactoring and bug fixes.
Reinstated some motion break out clauses in boost loop
as their removal hurt a few 50fps clips badly in the std set.
It may be possible to remove them again later if a better way
can be found of preventing overly long gf intervals.
Change-Id: Iee686d0c31072828bb1ccd2bc63f5f1c7c548ea2
7eb66d82ca