[FR] - Allow players and kibitzers to highlight a piece other than last-play

[dopeghoti]

In board games such as Hex or Go, allow players to use a command to "point at the board" to display to other players an instance of the board with the specified piece or location highlighted, as is done automatically for the "last-played-piece".

Allow Kibitzers to do the same, but by default, only other kibitzers see the highlighted board.
Allow players to decide to see kibitzers' highlights as an option.