Make LUT legend consistent between parametric map and fractional segmentations

[fedorov]

Parametric map

Fractional segmentations

Here are the specific improvements:

1. Make implementation consistent between parametric maps and fractional segmentations
2. Make color bar horizontal (to accommodate more easily situations where we have multiple items that use color maps)
3. Show text on the right of the horizontal color bar
4. Make sure numeric range is displayed for both, with minimum on the left
5. In the situations where we have multiple objects, stack up color bars and show "Property type" code meaning instead of "Fractional segments" shown right now
6. When there are multiple fractional segmentations/parametric maps, unless the color is specified in the object, assign different color maps to each segment.

@igoroctaviano can you review and let me know which ones are not easy to implement before you start working on this?

[igoroctaviano]

@fedorov 5, and 6. Let me know if I should handle the others.

[fedorov]

Let's proceed with 1-4 then. I will create separate issues for 5 and 6.