Add number of connected players to players command (#73)

Fixed the error where it cannot find an user at the notice hook. 
It happened when you get the `NOTICE * :*** Looking up your hostname and checking ident`
Because `*` is not in the `<nick>!<ident>@<host>`

botcmds.lua

@@ -169,8 +169,10 @@ irc.register_bot_command("players", {
 		for _, player in pairs(players) do
 			table.insert(names, player:get_player_name())
 		end
-		return true, "Connected players: "
-				..table.concat(names, ", ")
+		return true, string.format("%d connected player(s): %s",
+			#players,
+			table.concat(names, ", ")
+		)
 	end
 })
 

hooks.lua

@@ -171,7 +171,7 @@ end
 
 
 function irc.hooks.notice(user, target, message)
-	if user.nick and target == irc.config.channel then
+	if user and user.nick and target == irc.config.channel then
 		irc.sendLocal("-"..user.nick.."@IRC- "..message)
 	end
 end