fix: make characters drop their inventory on knockout

src/main/java/uulm/teamname/marvelous/gamelibrary/entities/Inventory.java

@@ -104,6 +104,13 @@ public class Inventory implements Iterable<StoneType> {
         content.clear();
     }
 
+    /**
+     * Removes all stones from the Inventory.
+     */
+    public void clear() {
+        content.clear();
+    }
+
     /** Iterates over the inventory. */
     @Override
     public Iterator<StoneType> iterator() {