Rework subme system, add RD refinement in B-frames

Rework subme system, add RD refinement in B-frames
The new system is as follows: subme6 is RD in I/P frames, subme7 is RD in all frames, subme8 is RD refinement in I/P frames, and subme9 is RD refinement in all frames.
subme6 == old subme6, subme7 == old subme6+brdo, subme8 == old subme7+brdo, subme9 == no equivalent
--b-rdo has, accordingly, been removed.  --bime has also been removed, and instead enabled automatically at subme >= 5.
RD refinement in B-frames (subme9) includes both qpel-RD and an RD version of bime.