name2rgb — returns the RGB values of a named color
rgb=name2rgb(name)
name2rgb returns the RGB values of a color given by its name. The result is
a vector [r,g,b] where r, g and b are integers between 0 and 255
corresponding to colors components red, green and blue. As usual 0 means no intensity and
255 means all the intensity of the color.
If no color is found [] is returned.
The list of all known colors is given by color_list.