- 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

This is JVET L0054 MMVD code.
MACRO is JVET_L0054_MMVD.

See merge request jvet/VVCSoftware_VTM!26

Squashed commit of the following:

commit d9b44c2820495aee7c77604f511116711a18b880
Author: seungsoo <ss00.jeong@samsung.com>
Date:   Fri Oct 26 08:28:35 2018 +0900

    code update ( reflection )

commit 1fd1b4341134f355651d950ba0024c2b370cdfb5
Author: seungsoo <ss00.jeong@samsung.com>
Date:   Thu Oct 25 10:59:22 2018 +0900

    code update ( reflection of commented things )

commit 3befe26e3e9c23c51bad6e874d868403f665f452
Author: seungsoo <ss00.jeong@samsung.com>
Date:   Wed Oct 24 13:18:27 2018 +0900

    JVET_L0054_MMVD is uploaded.