Add color sampler in part color manager to copy the color of another part when you click on it

[jclovis3]

After using several different color scheme for parts, it would be nice to be able to duplicate one of those when adding new parts by using the standard color sampler dropper icon to allow us to click a part and have its colors loaded into the color manager. It would also be helpful to have a scrollable list of color schemes used on the active vessel along the side of the color manager that you can expand and contract like a sideways window slider. Then we would more easily be able to select color schemes that are hidden by a shroud later in the build.