title: Add custom link to operations in 'admin/content'
body: <p>Can someone give me a suggestion on how to add another link to the "operations"-cell on admin/node?</p>
  
  <p>I have written a module which copies a specific node and now i need in addition to the links "edit" and "delete" a "copy"-link.</p>
  
  <p>Can´t find any useful hints in the Drupal API.</p>