Fix #1383: ALF APS management in multilayer streams

See merge request !1877

Fix decoding when using long term in the SPS RPL

See merge request !1863

Fix #1382: modify list construction and verification

See merge request !1876

Fix RPL construction: allow short-term to be marked as long-term (regression after !1868)

See merge request !1878

Check for IRAP instead of IDR/BLA/I-slice to determine whether APS
can be reused.
Check new chroma filter even if APS id was previously used in a
different layer

Move ILRPs before unusable reference pictures in RPL
Modify RPL verification to correctly handle ILRPs

JVET-S0047 and JVET-S0211: Add "_minus1" to VB pos SEs and signal num VBs with ue(v)

See merge request jvet/VVCSoftware_VTM!1874

Bugfix for Ticket #1291: Mismatch between spec and software in BPSEI and PTSEI

See merge request !1857

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

1. bp_cpt_cnt_minus1 in BPSEI not being parsed.
2. Number of signalled pt_du_common_cpb_removal_delay[i] and pt_du_cpb_removal_delay_increment_minus1[i][j] not being signalled correctly.
3. Inference rule for pt_sublayer_delays_present_flag[i] when bp_max_sublayers_minus1 is 0
4. Initialization of m_nuhLayerId = 0 in initSlice

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