* lisp/gnus/gnus-icalendar.el
(gnus-icalendar-event:recurring-interval): Fix parsing of weekly
recurring events (bug#43669).
Example: in the absence of explicit INTERVAL value in the calendar
event, a weekly event with occurrences scheduled for Mondays and
Wednesdays should receive the default recurring interval of "1" and the
org mode timestamp repeater should be "+1w".
Due to a bug in the current code we receive "WEEKLY" and "+WEEKLYw"
instead. The patch fixes the issue.
* test/lisp/gnus/gnus-icalendar-tests.el:
(icalendar-tests--get-ical-event): Remove unused function accidentally
copy-pasted from icalendar-tests.el.
(gnus-icalendar-parse, gnus-icalendary-byday):
Remove unintended initial newlines.
Duplicate comma-escaping backslashes so that they have intended
effects, conforming to RFC 5545.
Remove ineffective comma-escaping backslashes where not intended.
* lisp/gnus/gnus-icalendar.el
(gnus-icalendar-event:recurring-days): New function (bug#39782).
(gnus-icalendar-event:org-timestamp): New function.
(gnus-icalendar--find-day): Use them.
(gnus-icalendar-event--org-timestamp): Ditto.
