Add border-color to property list

The result of border-color is a string like "rgb(255, 0, 0) rgb(0, 0, 255) rgb(0, 128, 0) rgb(255, 255, 0)".
I remove the duplicates and only use the unique color values of "border-color" property.

Changed the placeholder for color (%c____%c => %c    %c). Otherwise you see the underscores on rgba colors.

What do you think about that? If you don't want parse the border-color maybe you can change the placeholder.