R4

• Use the new VapourSynth API V4
• Switch to 12-bit RGB HDR patterns (was shifted to 16-bit before)
• Tag 12-bit BT.2020 as 12-bit. No functional difference to always tagging it as 10-bit as before, but more correct.
• Update HDR patterns to ITU BT.2111-2
• Add 4fsc modes (digital composite)
• Add halfline blanking option to NTSC/PAL modes for extreme pedantry/authenticity
• Add SAR to frame properties
• Fix some compiler warnings