title: Adding field to Wordpress admin Quick Edit
body: <p>I have new client whose web site uses an older version of Jigoshop (0.9.9) that has
  had a lot of customization done to it. They want me to add the pricing field to the
  admin's quick edit panel for each product.</p>
  
  <p>The field name in question is 'regular_price'.</p>
  
  <p>How do I go about adding a custom field to the quick edit panel?</p>
  
  <p>Many thanks!</p>