Implement fast sync upon opening article

It would be nice to have fast sync occur when opening an article, to force a new fast sync, even though the five minutes interval have not passed (as described in the blog post here:
https://gist.github.com/nicosomb/1e2c7a05b0b20e131023e6dc7e654fb2).

This would make sure that any changes to an article, like changing the star status, tags etc. to be reflected in the article being opened. When the annotations will be properly synced in the future (as already reported in issue #1048 ), having the forced fast sync upon opening an article will definitely be a logical addition.

I don't know how the fast sync is implemented, but if a fast sync could be forced for just the article being opened, that would of course be preferable and make the sync even quicker.