From Ulf Jasper <ulf.jasper@web.de>:

From  Ulf Jasper  <ulf.jasper@web.de>:

(icalendar-version): Increase to 0.13. Now a string.
(icalendar-import-format): Handle CLASS, STATUS, URL. Rename
`subject' to `summary'.
(icalendar-import-format-summary): Rename from
`icalendar-import-format-subject'.
(icalendar-import-format-url, icalendar-import-format-status)
(icalendar-import-format-class): New variables.
(icalendar--rris): Take variable argument list.
(icalendar--datestring-to-isodate): Remove unnecessary
calendar-style check when converting dates with explicit month
names.
(icalendar-export-region): Change return type of conversion
subroutines.  Bury current buffer unless error occurred.
(icalendar--convert-to-ical)
(icalendar--parse-summary-and-rest): New functions.
(icalendar--convert-ordinary-to-ical)
(icalendar--convert-weekly-to-ical)
(icalendar--convert-yearly-to-ical)
(icalendar--convert-block-to-ical)
(icalendar--convert-cyclic-to-ical)
(icalendar--convert-anniversary-to-ical): Change return type.
Strip trailing blanks from subject.
(icalendar--convert-sexp-to-ical): Change return type.
Strip trailing blanks from subject.  Handle simple sexp
entries as generated by icalendar.el.
(icalendar--convert-float-to-ical)
(icalendar--convert-date-to-ical): Strip trailing blanks from
subject.
(icalendar-import-file): Doc fix.
(icalendar--format-ical-event): Handle CLASS, STATUS, URL.
Correct call to icalendar--rris.
(icalendar--convert-ical-to-diary): Doc fix.  Rename `subject' to
`summary'.
(icalendar--add-diary-entry): Rename `subject' to `summary'.