add BlackJack environment and fix save and load

- method names were swapped

src/main/java/evironment/blackjack/cards/CardDeck.java

@@ -0,0 +1,34 @@
+package evironment.blackjack.cards;
+
+import core.RNG;
+
+import java.util.ArrayList;
+
+public class CardDeck {
+    private ArrayList<Card> cards;
+
+    public CardDeck() {
+        cards = new ArrayList<>(Suit.values().length * Rank.values().length);
+        for(Suit s : Suit.values()) {
+            for(Rank r : Rank.values()) {
+                Card c = new Card(s, r);
+                cards.add(c);
+            }
+        }
+    }
+
+    /**
+     * We assume that cards are dealt from an infinite deck (i.e., with replacement)
+     * so that there is no advantage to keeping track of the cards already dealt.
+     * Therefore no card is removed from the deck.
+     *
+     * @return next card
+     */
+    public Card nextCard() {
+         /*
+            nextInt(int bound) returns random int value from (inclusive) 0
+            and EXCLUSIVE! bound
+          */
+        return cards.get(RNG.getRandom().nextInt(cards.size()));
+    }
+}