* gnus.el (gnus-parse-headers-hook): New hook.

* gnus.el (gnus-parse-headers-hook): New hook.
(gnus-get-newsgroup-headers): Call it.
(gnus-get-newsgroup-headers-xover): Call it.
(gnus-group-mode-map): Moved `gnus-group-fetch-faq' from `M-f' to
`H f'.
(gnus-summary-copy-article): Allow respooling to any backend.
(gnus-summary-set-process-mark): Make sure each article can only
be process marked once.
(gnus-summary-remove-lines-marked-with): Put point on a valid
article after removing lines.
(gnus-summary-sort-by-author): Didn't allow sorting when
pseudo-articles were present.
(gnus-summary-sort-by-subject): Ditto.