JVET-S0047, JVET-S0211: Add _minus1 to virtual boundary pos SEs and signal num virtual boundaries with ue(v) in SPS and PH.

Fix syntax order of sublayer_hrd_parameters() to align with specification

See merge request jvet/VVCSoftware_VTM!1872

JVET-S0172 item 2: Constraints on GCMP

See merge request jvet/VVCSoftware_VTM!1843

JVET-R0251 aspect 1: Renaming sps_XXX_pic_present_flag to...

See merge request jvet/VVCSoftware_VTM!1871

JVET-R0251 aspect 1: Renaming sps_XXX_pic_present_flag to sps_XXX_control_present_in_ph_flag for bdof, dmvr and prof.

JVET-R0249: Prefix syntax elements in the VPS, SPS, PPS, PH, and SH with vps_,...

See merge request jvet/VVCSoftware_VTM!1866

Fix for ticket #1373: Repeated conversion of the Intra Chroma minQT setting from chroma unit to luma unit for multiple SPSs

See merge request !1870

Removed the macro JVET_R0249_SE_PREFIXES since the changes in this merge request only comprises renaming syntax elements and variables.

from chroma unit to luma unit for multiple SPSs

Fix decoding if bitstream starts with a CRA picture with RASL

See merge request !1868

JVET-R0227 aspect 3: Rename gci_no_qp_delta_constraint_flag to gci_no_cu_qp_delta_constraint_flag

See merge request !1869

Allow build with OpenMP on macOS/Xcode

See merge request !1865

- rewrite xGetRefPic() and xGetLongTermRefPic() to return a nullptr, if picture is not found
- run conformance checks only on existing reference pictures
- reset picture based variables if RASL picture is skipped

Fix intra-layer references in enhancement layer IRAP

See merge request !1867

JVET-R0249: Prefix syntax elements in the VPS, SPS, PPS, PH, and SH with vps_, sps_, pps_, ph_ and sh_ and rename ph_disable_xxx_flag to ph_xxx_disabled_flag.

For the syntax elements for which a prefix was added it was also made sure in this commit that the name of the syntax element aligns with the specification. For instance was rpl1_copy_from_rpl0_flag renamed to sps_rpl1_same_as_rpl0_flag.

OpenMP is not included in the system clang compiler. Recent CMake is able to
find OpenMP installations with brew and provide proper configuration info. OpenMP
should be detected after:

  brew install libomp

(require CMake >3.12)

Cleanups and fixes for software manual / remove unused encoder option

See merge request !1864

Fix cfg files for field coding

See merge request !1862

JVET-S0097: set default values in VPS

See merge request !1861

Set default values when the bitstream does not contain any VPS

Fix #1320: Add process for decoding NAL_UNIT_FD when filler data NAL units are in the bitstream

See merge request jvet/VVCSoftware_VTM!1859

Fix segmentation fault when decoding a VPS after 07afae5e

See merge request !1860

Indeed m_vps is equal to nullptr when parsing the first VPS

Fix for Ticket #1319 - encoder is crashed when setting DecodingRefreshType equal to 2

See merge request !1858

fix ticket 1320: Missing the process of decoding NAL_UNIT_FD when filler data NAL units are in the bitstream

Refactor/Bugfix: VPS handling

See merge request !1473

- create a "dummy" VPS with ID 0 on first access in ParameterSetManager
- actually use the "dummy" VPS
- improve DecLib::m_vps handling (may still fail if multiple VPSs are in the bitstream)

Bugfix and code cleanup for Ticket #1095.

See merge request !1661