Review management of current article selection
Review management of current article selection

In order to fix more easily issue #924, we simplify the management of
the article whose display we want to preserve on updates.
May help on issue #601 too.

josh64x2/vienna-rss,ViennaRSS/vienna-rss,barijaona/vienna-rss,ViennaRSS/vienna-rss,ViennaRSS/vienna-rss,josh64x2/vienna-rss,barijaona/vienna-rss,barijaona/vienna-rss,ViennaRSS/vienna-rss,barijaona/vienna-rss,josh64x2/vienna-rss,ViennaRSS/vienna-rss,barijaona/vienna-rss,lapcat/vienna-rss,Eitot/vienna-rss,lapcat/vienna-rss,Eitot/vienna-rss,josh64x2/vienna-rss,lapcat/vienna-rss,Eitot/vienna-rss,josh64x2/vienna-rss,Eitot/vienna-rss,lapcat/vienna-rss