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

Detail
- Group the dual tree related syntax elements together in the SPS (JVET-S0132 aspect 1)
- Rearrange the partition constraint related syntax elements in the SPS (JVET-S0132 aspect 2)
- Rearrange the syntax elements related to inter slices in the PPS (JVET-S0132 aspect 3)

32-bit accumulation is required for ALF filter to avoid overflow,
even when coding 8- and 10-bit video.
Only non-SIMD code is affected (which is generally not used)