[yktbrwrc] Graphical evaluation scores of available moves

Annotate origin and destination squares of good moves of a given chess position with unobtrusive marks.

It is in general ambiguous exactly what move is being suggested, so it only provides a hint.

Goal is the avoid the spaghetti of confusion if every available move were marked with an arrow of a different color depending on evaluation (with a nod to Alice's Restaurant). Broadcast of a game in progress.

Go further than 1 ply. This provides further hints of important pieces and squares which get marked often.