[BZ#698499] refresh view automatically when files appear or disappear in underlying directory

Submitted by Adam Dingle

Description

In Meld's directory comparison and version control views, I must use View->Refresh or View->Reload to refresh the view when the set of files in the underlying directory has changed. It would be nicer if Meld refreshed the view automatically, just like Nautilus does when files appear in a directory you're viewing there.