Support detailed judgments per judge (ballots) as input as well

[domi41]

Support a CSV with the (anonymized) individual ballots as input:

    Pizza,  Pasta, Chips
excellent,   good,  poor
very good, reject,  poor
…

Grade detection may be complex (or impossible in some cases).
We can try our best with preset gradings (:lion: :warning: ), but we'll need a --grades flag to let users set their grades.

There's also the possibility of using the first line of the CSV as grading, like so:

reject, poor, good, very good, excellent
    Pizza,  Pasta, Chips
excellent,   good,  poor
very good, reject,  poor
…

This would start a big development arc, since there will be many possible plots from such detailed data.

We also need to detect which form of the CSV is used as input, and that's not going to be pretty.