Use IItemHandler instead of IInventory internally (#2971)

* Use IItemHandler instead of IInventory internally

src/main/java/appeng/util/inv/IMEAdaptor.java

@@ -49,6 +49,12 @@ public class IMEAdaptor extends InventoryAdaptor
 		this.src = src;
 	}
 
+	@Override
+	public boolean hasSlots()
+	{
+		return true;
+	}
+
 	@Override
 	public Iterator<ItemSlot> iterator()
 	{