title: Sitecore extend version diff popup
body: <p>Sitecore version diff popup is used to compare fields among versions of an item. But as a default it only shows user defined fields of that item(non standard fields). There is a requirement from my client asking to show comments provided by administrators when taking some actions through workbox in the version diff popup. I know that these information are saved in workflow history separately from item. Is there a way I can show these workbox information in version diff?</p>