whist.pl -- play whist via IRC

whist.pl is not fully tested, mostly because I don't have anyone to play with me. The IRC channel it was written for died long ago.

So it goes.

Play is initiated with the !deal command. Other players join with !join; play starts immediately when there are four players.

A card is thrown in brackets, with number and suit, e.g. [3d] for the three of diamonds, or [as] for the ace of spades.