add SONY CXA2025AS YUV decoder present

[zack867]

According to page 17 of public SONY CXA2025AS Datasheet PDF.
It has a R-Y G-Y axis selector switch to switch axis angle for JAPAN NTSC-J and US NTSC-M
JP : R-Y: 95° * 0.78 G-Y: 240° * 0.3 B-Y: 0° * 1
US : R-Y: 112° * 0.83 G-Y: 252° * 0.3 B-Y: 0° * 1
Since nestopia already support native YUV decoder function,
I think it's a good idea to include SONY CXA2025AS-JP and SONY CXA2025AS-US present.

[carmiker]

I think it's a jolly good idea. I'm experimenting right now, and these numbers produce a nice palette in both cases. The US version is slightly different from the included SONY_CXA2025AS_US.pal. I suppose the YUV generator may be more accurate than this palette which I believe was handcrafted.

[carmiker]

These are added to the core now, and are currently usable in the FLTK frontend (and upstream in Nestopia JG). I've removed the old .pal based CXA2025AS option, but it is still loadable as a custom palette.