Optimize layout using Opacity if no color is selected

[hski-github]

If no color is selected, it is not so easy to see, where the lines are going. It might be useful to introduce border color or opacity.

[hski-github]

A slight introduction of opacity:0.9 would help a little, but would still preserve the color.

[hski-github]

path.setAttribute("style", "fill:" + rowcolor + ";opacity:0.9;");

Could also be a configuration parameter for the Sankey mod to set opacity to 1.0, 0.9, 0.8 or 0.7.

[hski-github]

See also example of Sankey with opacity. Color is defined via bars, and the flows have opacity of the original color. https://github.com/samirsaci/visuals_analysis/blob/main/Sankey%20Chart.ipynb