gnus-art.el (gnus-article-browse-html-*): Work for broken Chinese articles
gnus-art.el (gnus-article-browse-html-parts): Replace LWSPs with `&nbsp;'s in header
Allow overriding charset in some decoding functions
* gnus-icalendar.el (gnus-icalendar-event-from-ical)
(gnus-icalendar-event->org-entry) (gnus-icalendar--update-org-event)
(gnus-icalendar-event->gnus-calendar): Distinguish between
required/optional/non-participant attendee status. Fix bug causing the
first required event participant to be omitted.