Results graph: see changes made since last round

[ggordn3r]

We want to visually emphasize eliminations and changes in weights between rounds.

The bars

• An increase in weight since last round should be illustrated with a new color (hex 61E786)
• A decrease in weight since last round should be illustrated with a new color (hex EF8F57)

See image below for a similar implementation from another RCV tool.

New text

• Changes in weight should also be indicated with text, as below
• The last eliminated candidate should be indicated in text, as below

[ggordn3r]

Looks great! @iambateman I can appreciate leaving out the text additions to avoid clutter. However, I find myself scrolling around and doing the math in my head from round to round, especially when vote totals are active. Try it with this poll: https://rankit.skelpo.com/results/0s4l9EbBvhOY1PGgv3Ms/summary

I've let Emily know that this is ready for her review. Let's see what she thinks.