Override the repr for the Human strategy.

[drvinceknight]

Closes #958.

[marcharper]

This is fine but perhaps there's a better place for c_symbol and d_symbol -- maybe in the Actions class. There are similar parameters for sparklines (in Match).

[drvinceknight]

👍 I'm throwing the ready to merge label on this (and have done on #955) as a visual prompt to Owen but please throw it off if you had left it off on purpose because you wanted to look at it again.

P.S. Open to moving the symbol commands (although they feel natural to me here from a UI pov, and perhaps could interface to the Actions class on #816 when we get to that).

[marcharper]

I'm fine with merging this.