added demo game in chris_demo

You had some really clear planning in your commit message--
In the "chris_demo" folder I implemented a bunch of what
you planned. I suggest playing the game I built
(go into chris_demo and run python game.py), and then
carefully reading all the source code. Then, if you like
the patterns I used, copy or move whatever you want
to use into your main project folder. Also, if there
are parts of my code you don't understand, please let
me know (in a commit message or in person next time
I'm in class) and I'll be happy to explain it.

chris_demo/deck.py

@@ -0,0 +1,20 @@
+from card import Card
+from random import shuffle
+
+class Deck:
+    def __init__(self, position, hidden=True, shuffled=True):
+        self.position = position
+        self.cards = [Card(position, i, hidden=hidden) for i in range(52)]
+        if shuffled:
+            shuffle(self.cards)
+
+    def draw(self):
+        return self.cards.pop()
+
+    def get_agents(self):
+        agents = []
+        for card in self.cards:
+            agents.append(card)
+            agents += card.agents
+        return agents
+