- tiles are in the VVC spec for 3 meeting cycles now
- cleanup helps with adaptation for tiles to current draft

- 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

Use a single array with elements that comprise scan x position, y
position, and index into block instead of separate arrays.

Simplify array initialization code

There is a conflict with JVET_M0427_INLOOP_RESHAPER that is triggering a debug assertion that checks that the width is not 1.

Two changes are included: (1) disable fractional MVD for UHD sequences (M0312 & M0255) (2) encoder optimization for MMVD

Fix of ticket #98 on incorrect derivation of chroma-tree split context. Patch provided by adam.wieckowski@hhi.fraunhofer.de