Scalar Bar with a Color Range Drop Down

[noverney]

There is a popup.scala file which can be run which loads a femur that you can play around with both files will not be necessary in the final version

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[marcelluethi]

Thank you very much for this PR. This is a very nice prototype and it clearly shows the way how a ScalarBar can be implemented. Testing shows that it works in principle, but there are still some minor problems.

• Compilation currently fails on modern java versions, (see travis log)
• Changing the color scheme only updates on reloading the scalar bar
• Changing the color bar seems to change the scalar range of the sliders
• A changeable background color would enhance readability

I think these problems could be easily fixed and that we should work on fixing these problems and integrating this feature into scalismo-ui. What do others think?

As the PR cannot be merged in this form, I will close the PR and propose to work on it on a separate branch.