build color picker

The color picker should be used to edit the value of a color constant or color fader column. It needs to be available in the filter editor for configuring a constant, in the show mode UI for a linked constant or in the popup / overlay when a column is selected.

As a basis, there exists the QColorDialog which can be used but it requires some tweaking and integration. First of all it allows picking colors from HSV and not from HSI color space. Furthermore it does not allow picking colors from a gamut diagram nor from cmyk. The inclusion of RGB color codes is nice but the button to pick a color from the screen might not be required (It won't hurt though). Also it needs to support UV settings of a fixture. Last but not least it seams to be a meant purely as a dialog window and would benefit from some integration with the control desk.