Some icons (modern settings, jump-list tasks) are monochrome, basically
they are defined just by alpha channel.
Thus they can be displayed in any color (white is default).
Since these icons are white by default, they look nice on dark
backgrounds. But they are not very visible on light backgrounds.
Thus the idea is to 'colorize' such icon using color of corresponding
text item. That way they will always have proper color.
Fixes#466.
