#4 "R/G/B" labels for ColorPicker plugin sliders

[Rene Zanner]

The sliders in the ColorPicker plugin do not have a label describing it's purpose.
Minimum is the first letter of the color being changed by the specific slider, that is an "R" for "red" in front of the first slider, a "G" for "green" before the second slider and a "B" for "blue" before the third slider.