Add support for a random pick from a selection of cards

!card now accepts a comma-separated list of numbers from which it will
select one randomly, with equal probability. This selection is made
before the card event is sent out and is fully transparent to the rest
of the game logic.

botcmd.py

@@ -5,6 +5,9 @@ import channel
 
 import gameloop
 
+import random
+import re
+
 nickserv_pass = None
 irc_chan = None
 
@@ -139,7 +142,7 @@ def usage(command):
 		elif command[0] == 'kick':
 			return 'Usage: !kick <nick>'
 		elif command[0] == 'card':
-			return 'Usage: [!card] <number> ...'
+			return 'Usage: [!card] <number[,number,...]> ...'
 		elif command[0] == 'deck':
 			return 'Subcommands: !deck add | remove | list'
 		elif command[0] == 'bot':
@@ -190,6 +193,9 @@ def parse_command(message, nick, irc):
 
 		return message[index:]
 
+	def valid_choice(c):
+		return re.fullmatch(r'\d+(,\d+)*', c)
+
 	events = gameloop.events
 
 	message = message.split()
@@ -323,17 +329,23 @@ def parse_command(message, nick, irc):
 			else:
 				send_event((events.limit, gameloop.limit_types.points, num))
 
-	elif c == '!card' or all(i.isdecimal() for i in message):
+	elif c == '!card' or all(valid_choice(i) for i in message):
 		if c == '!card':
 			args = message[1:]
 		else:
 			args = message
 
-		if not all(i.isdecimal() for i in args):
+		if not all(valid_choice(i) for i in args):
 			send(usage('!card'))
 			return
 
-		choices = [int(i) for i in args]
+		def pick(c):
+			if c.isdecimal():
+				return c
+			else:
+				return random.choice(c.split(','))
+
+		choices = [int(pick(i)) for i in args]
 		send_event((events.card, nick, choices))
 
 	elif c == '!cards':