SCART/VGA 15KHz output and NTSC Colour Space Fixes

I should be doing something else, so I've decided to get SCART / 15KHz RGB output working. In theory, this is quite simple, as all the machinery for 15KHz video is already there for the PAL/NTSC composite output stuff. While I have my head in this bucket, I've also take a moment to look at the remaining NTSC colour space bugs. Generating the SCART 15KHz video signal is in theory very simple:…