Incorporate Sankey diagrams for IRV/RCV elections

[robla]

There has been a number of uses of Sankey diagrams to show the result of IRV/RCV elections (see below). It would be cool to incorporate a Sankey implementation into awt.

Implementations for RCV:

• https://github.com/chrisroat/pyrcv
• https://sniplets.org/rankedResults/
• https://github.com/artoonie/rcvis