JVET-S0115 aspect 2 (JVET-S0142 item 4): Change the name and semantics of vps_all_layers_same_num_sublayers_flag (to be vps_default_ptl_dpb_hrd_max_tid_flag) to only control VPS syntax without requiring the number of sublayers to be the same for all layers.

Aspect 1: Remove the extra_sh_bits_struct( ) and extra_ph_bits_struct( ) structures and put their content directly in the SPS.

Aspect 6: Modify the derivation process for the variable TotalNumOlss by removing unnecessary text.

Also renamed 'numReorderPics' variables to 'maxNumReorderPics'

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

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

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

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

- 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

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.

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

- 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)

JVET-S0100 Aspect 3: constraints on vps_dpb_max_tid and vps_hrd_max_tid depending on vps_ptl_max_tid

Merge

These changes should not affect any bitstream

(1) move frame_only_constraint_flag and single_layer_constraint_flag outside the GCI syntax structure into the PTL syntax structure
(2) rename single_layer_constraint_flag to multi_layer_enabled_flag
(3) change ptl_alignment_zero_bit to ptl_reserved_zero_bit

- Rename members of WPScalingParam to conform to guidelines
- Avoid casts from const to non-const types
- Modify getWpScaling function to handle case where the reference
  index is negative (see #733)
- Add helper function isWeighted to determine whether weighting
  parameters are present for any colour component
- Fix some indentation issues