- Add support loading custom palettes (restored from upstream)
- Add composite palette, switchable as a core option to select default
rgb colors or composite (experimental)
In order to accomodiate the feature, colormap or LUT is used instead of
usin MAKECOLOR_PCE.
https://github.com/libretro/beetle-pce-libretro/issues/6
…ithub.com/libretro/beetle-pce-libretro/pull/7)