Fix QColorPickerElement getImageFromItem: method

The `getImageFromItem:` creates an image for the selected item, but it gets the description of the selected item before checking if that item is a UIColor. Because of this, if your item actually is a UIColor, you just end up with a black circle.

Oh, and while I was at it I fixed up the default items for a QColorPickerElement. Some of the names and colors got mismatched.