Add "Declare Victory" feature

[mgaree]

Sometimes, the game is obviously over but many cards are left in a hand to play. It would be nice to have a way to declare the game as over and not have to play out the rest of the hand.

Would require a button on the client that all player have to press (AI would have to automatically concur). When all players agree, the game would end. It could be handled by enabling a client-side function to make the first available legal play whenever the client is the active player, sort of like a RandAI feature for the client. By turning off animations automatically, the everyone's cards could be played out and normal server-side game handling would not need to be changed.

Alternatively, declaring victory would issue a special command to core.game and cause the game to end.

Low priority.