Enables custom fields in revisions and makes preview work as expected when using custom fields.
If you want the "Compare revisions" feature in WordPress to show differences in your custom fields there is a patch included in the assets folder. The plugin will work fine without this hack but for now this is included until I find a way of acheiving the feature. Use at own risk! :)
You need to apply the revision.patch to wp-admin/revision.php and check the box under Advanced section in the plugin settings page to get it working.
IMPORTANT: Do not check the box UNLESS you have applied the patch. It will make the plugin work incorrect.