Overflow may occur in corner cases in large pictures.
Added const modifiers where appropriate.
Defined additional variables to hold intermediate values to avoid
code duplication.
Rename variables to more closely match VVC specification.

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

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.

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

JVET-S0048 Aspect2: change the constraint on the value ranges of scaling window offsets to be more flexible

Silence warnings for potentially invalid array indexes by adding explicit checks.

renamed the getWideAngleIntraMode function as well

store sub-picture numbers, sizes, and locations with a picture, so that they can be fetched directly from redPic