Modify interpolation filter function such that, when processing a
chroma block, the fractional displacement is always expressed in
units of 1/32nd of a chroma sample.

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

Fix the prefix problem of some variables names; change the macro from ACT_LMCS_FIX to JVET_S0234_ACT_CRS_FIX.

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

   - Move wrap around offset from SPS to PPS.
   - Disable wrap around for any reference pictures that require RPR scaling.