#29 Human leaves game in progress: options

[Klint]

When a human abandons the game, instead of the
automatic replacement of the human with a bot, it
would be nice to have two buttons: one to remove the
player (but not the pieces on the board) and continue
with the remaining players; another to bring in a bot.

If game-owner control is established, the button could
be restricted to that player's use only; if not, then it
could be a switch (or two) that all current players would
have to activate for the event to occur.

-K