Auto-detecting SCART/15KHz Cables

If you have a MEGA65, you'd probably like to be able to plug a SCART cable on to the VGA port and have it Just Work :tm:, causing the MEGA65 to drive 15KHz video. Then if you plug in a normal VGA cable, you'd like regular 31KHz video still, right? To make this small miracle reality, I've modified a MiSTer SCART cable by putting a 2K Ohm resistor between pins 12 and 15. Those pins are used for the…