* avandu.el (avandu-new-articles-count): Only show a message in the
echo area if it has been called interactively in any way.
(avandu-overview-mode): Set MODE-NAME to the format of
"Avandu:Overview[#]" where `#' is replaced by the number of unread
articles.
This command gets the api level from tt-rss, this doesn't serve any
purpose yet, but it could be used later-on to determine which features
are and aren't available.