Improvement: Show time of last reload/change in preview

[vbrdev]

Sometimes one can wonder if a change has been succesfully reloaded in the preview/HTML view. It would be great if the last rst change/reload time would be displayed. E.g. in a status bar at the end of the widget.

It would be great if this process could be animated. After reloading the rst file the time stamp is shown green (success) or red (failed/errors) for e.g 2 seconds. So the user could see that something happened.