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