fixes encoder/decoder mismatch with slices enabled, when merge candidates
are determined and the neighborig partition is triangle

also relevant for current tile design

This is for the case where JVET_M0464_UNI_MTS is disabled

fixed an encoder/decoder mismatch for multiple slices/tiles

Code was salvaged from !306

Clear entire buffer to ensure all values in the buffer are valid
even though some values may lie outside the subset of coefficients
that is effectively coded

Merge functionality from HM (macro JCTVC_Y0038_PARAMS). Add an additional
configuration file parameter that allows re-sending parameter sets at every
random access point.

Speed-Up for ISP when JVET_M0464_UNI_MTS is enabled. It can be enabled/disabled with the config. file parameter ISPFast.

When enabled,
-it merges all full RD intra mode lists into one,
-it tests fewer non-DCT-II transforms if ISP is likely to become the best mode and
-it stops testing intra modes for an ISP split if all sub-partitions obtained a zero-cbf.

Results in CTC:

AI -> 0.04% loss, EncT = 97%, DecT = 100%
RA -> 0.01% loss, EncT = 99%, DecT = 100%

patch from issue191 (without macro)

Fix ticket #153 on using uninitialized interDir and GBI array when MaxNumMergeCand=1 and MMVD uses the second merge candidate as base MV.

compositeRefEnabled is an encoder only option. It should not be stored in the SPS.
This commit is the last to remove unused parameters from SPSNext. Thus also
all comments related to SPSNext are removed.

Started failing after merging !294

AMVR (formely IMV) now has only one mode, which used to be mode #2
- remove SPS imv_mode parameter
- remove encoder configuration for mode #1 (mode #2 replaces mode #1)
- adapt config files to refer tp mode #1
- rename SPS syntax elements and access functions to AMVR

Note: IMV to AMVR renaming in other parts of the software should be done by proponents.

  - Sub-PU TMVP can generate an invalid inter candidate.
  - Simplify previous solution and eliminate duplicated code.