title: Magento: Display products from childcategories if parent category is empty
body: <p>I have the following categories</p>
  
  <p>Car parts (0)
    Tires (0)
      Rims (5)</p>
  
  <p>Now in the product listing obviously the car parts en tires listing returns 0 products. But for the user this is ankward. Is it possible to show child items if a category is empty?</p>
  
  <p>Kind regards</p>