Variable: list-colors-sort

Color sort order for `list-colors-display'.
`nil' means default implementation-dependent order (defined in `x-colors').
`name' sorts by color name.
`rgb' sorts by red, green, blue components.
`(rgb-dist . COLOR)' sorts by the RGB distance to the specified color.
`hsv' sorts by hue, saturation, value.
`(hsv-dist . COLOR)' sorts by the HSV distance to the specified color
and excludes grayscale colors.
`luminance' sorts by relative luminance in the CIE XYZ color space.