new color map code, based on a BSD-3 licensed module

[rozyczko]

Description

Replaced QrangeSlider module with bad licensing (GPL) with similar module with good licensing (BSD).
Improved behaviour and visuals as well.

Fixes #1944

How Has This Been Tested?

Tested on Win10

Review Checklist (please remove items if they don't apply):

• Code has been reviewed
• Functionality has been tested
• Windows installer (GH artifact) has been tested (installed and worked)
• MacOSX installer (GH artifact) has been tested (installed and worked)
• User documentation is available and complete (if required)
• The introduced changes comply with SasView license (BSD 3-Clause)

[lucas-wilkins]

Looks good

[wpotrzebowski]

Looks good and works on Mac. These are not really related to this PR, however the list of color maps is unneceserally long and one can input min value higher than max (withouith reversing map). Probably this condition can be changed but I wouldn't worry about it. Also I am wondering what should interaction for reseting to very initial values (it now remembers values from previous setup). Should "Home" from navigation menu do that?

[rozyczko]

the list of color maps is unneceserally long

I think it makes sense to enable users to use all the available color maps from the MPL dictionary.
Otherwise, we would have to do some categorisation and I don't really know which of those maps are common and which are not...

one can input min value higher than max (withouith reversing map).

This, actually, was a serious UI issue. Fixed.

Also I am wondering what should interaction for reseting to very initial values (it now remembers values from previous setup).

Without rewriting a large part of the code I don't see how this can be easily achieved. If you close the widget and then reopen it, the values come back to the original numbers, though.