Show updated items as unread even if it was marked as read

[Al.]

Binary package hint: liferea

This is feature request. I think this is important in some cases. Let me explain.

For example i have feed from bbc. I've read everything and it's now marked as read. But sometimes one item in feed may be updated later (e.g. title changed, some content changed). I this case this item will be still marked as read and i skip those update. I suggest mark this item as unread and highlight difference (like in NetNewsWire on Mac). Show removed content using red striked out font and new content using green font and not changed content as regular font. Example - http://entertainmentweakly.com/obamaweird.gif