Added 'Visitor' interface.

Added the 'Visitor' interface to this project. It will be used to handle all types of power cards.

Projekte/mdga/model/src/main/java/pp/mdga/visitor/Visitor.java

@@ -0,0 +1,39 @@
+package pp.mdga.visitor;
+
+import pp.mdga.game.card.HiddenCard;
+import pp.mdga.game.card.ShieldCard;
+import pp.mdga.game.card.SwapCard;
+import pp.mdga.game.card.TurboCard;
+
+/**
+ * This interface will be used to realize the visitor pattern inside the application.
+ */
+public interface Visitor {
+    /**
+     * This method will be used to visit the given card parameter.
+     *
+     * @param card as a TurboCard object.
+     */
+    void visit(TurboCard card);
+
+    /**
+     * This method will be used to visit the given card parameter.
+     *
+     * @param card as a SwapCard object.
+     */
+    void visit(SwapCard card);
+
+    /**
+     * This method will be used to visit the given card parameter.
+     *
+     * @param card as a ShieldCard oblect
+     */
+    void visit(ShieldCard card);
+
+    /**
+     * This method will be used to visit the given card parameter.
+     *
+     * @param card as a HiddenCard object.
+     */
+    void visit(HiddenCard card);
+}