Added dispenser event.

src/main/java/org/bukkit/inventory/ItemStack.java

@@ -194,6 +194,11 @@ public class ItemStack {
         return item.getAmount() == getAmount() && item.getTypeId() == getTypeId();
     }
     
+    @Override
+    public ItemStack clone() {
+        return new ItemStack(type, amount, durability);
+    } 
+    
     @Override
     public int hashCode() {
         int hash = 11;