JVET_O0594/O0252/O0506/O0615/O0624: BDOF reference sample padding using nearest integer sample positions

JVET-O0055 integer-distance DMVR cost to disable BDOF and disable BDOF early-termination in all cases

Cache is enabled incorrectly in DMVR processing

- add braces as suggested
- improve indentation of "else" branch
- fix consistently weird line breaks in clipMv function calls

Always using six tap filters for affine blocks no matter whether all CPMVs are the same. Patch provided by minhua.zhou@broadcom.com

Fix the memory leak caused by allocating memory for m_cYuvPredTempDMVRL0 and m_cYuvPredTempDMVRL1 multiple times at decoder.

Changed computation of deltaIntMvX and deltaIntMvY based on un-clipped
MVs instead of clipped MVs

When MC for luma only is desired, use existing luma/chroma parameters
instead of encoder-specific field in data structure

Also take care that luma only MC doesn't imply IBC

- all elements of SPSNext are moved into SPS
- syntax elements of SPS are sorted according to draft (as far as possible)
- comments were added where software and draft diverge