Merge

During integration of JVET-R0324, mvd_l1_zero_flag was moved down
in the syntax table (see JVET-R2001-v2). This change had not been
reflected in the !1563.

These changes should not affect any bitstream

gci_no_rectangular_slice_constraint_flag,
gci_one_slice_per_subpic_constraint_flag,
gci_no_subpic_info_constraint_flag and remove
gci_one_subpic_per_pic_constraint_flag

(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

JVET-S0066: gci_three_minus_max_log2_ctu_size_constraint_idc and gci_no_luma_transform_size_64_constraint_flag

Rename syntax elements to match spec and add range checks.
This should address JVET-S0130 aspect 1 (JVET-S0144 item 9.a)

Also fixes #738

- 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

Move the signalling of aps_params_type to an earlier position and change the signalling of aps_adaptation_parameter_set_id

AHG Recommendation (cleanup): Just change the order to put the type before the ID.

JVET-S0183 VPS information signalling modification: signal num_output_layer_sets_minus1 as num_output_layer_sets_minus2

Made changes to constraints for chroma format and bit depth, according
to meeting notes on JVET-S0094.
Also added encoder and decoder side checks.

JVET-S0181: Reference picture list information signalling cleanup - signal ltrp_in_slice_header_flag[listIdx][rplsIdx] only when num_ref_entries[listIdx][rplsIdx] is greater than 0 in addition to other conditions.

Move no_output_of_prior_pics_flag from PH to SH

JVET-S0186: VPS cleanup - move 2 syntax elements, sps_chroma_format_idc and sps_log2_ctu_size_minus5, to take the place of sps_reserved_zero_4bits.