UX Improvements

[hwatheod]

Copied from an email from Andrew Buchanan from 2021-06-15:

The number one thing I would like to see is a UX feature to just be able to "drive through".

By this I mean, if I click a retraction, I would like to see immediately what the next set of retractions
are. I don't want to still the old set of retractions which I've already clicked one of, as I get confused
whether I've done anything and who's to retract next.

I rarely need to change the solve parameters, so there is no reason for me to have to go through the Solve
button. I always set solve depth 1, because that's most interactive, and then max solutions very high,
because it can't slow the computation down, and it's always distracting if I find that I've set it too low.

In the longer term, I would appreciate graphical input, so I can see all the legal retractions shown on the
board. Each each retractable piece would have a colour blob on it, and if I mouse over then I can see what
the options are. Such a colourization feature would also make it really obvious who's to retract next.