* gnus-agent.el (gnus-agent-fetch-group): Go online if offline.

* gnus-agent.el (gnus-agent-fetch-group): Go online if offline.
(gnus-agent-summary-fetch-group): New command and keystroke.

* gnus-art.el (gnus-insert-mime-button): Tiny clean-up.
(gnus-mime-display-security): Make it respect
gnus-unbuttonized-mime-type-p.

* gnus-sum.el (gnus-articles-to-read): Comments.
(gnus-article-marked-p): New function.
(gnus-summary-display-make-predicate): New function.
(gnus-select-newsgroup): Use them.