Deck and joker constructor

Joker constructor takes a rank for uniqueness - rank doesn't really
change anything in terms of the "power" of a joker but helps with
ensuring jokers are unique in a deck.

Deck constructor takes an optional argument for the number of decks.
A deck includes two jokers, so n decks include 2n jokers.

packages.lisp

@@ -43,7 +43,9 @@
    ;; Comparators
    :suit< :rank< :card<
    ;; Serialisers
-   :suit->str :rank->str :card->str :cardset->str))
+   :suit->str :rank->str :card->str :cardset->str
+   ;; Constructors
+   :make-joker :make-deck))
 
 (defpackage cantedraw.main
   (:use :cl :cantedraw.lib.macros :cantedraw.lib.functions)