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

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

(icalendar--weekday-array): New constant.
(icalendar-weekdayabbrev-table)
(icalendar-monthnumber-table): Delete.
(icalendar--get-month-number): Use calendar-month-name-array.
(icalendar--get-weekday-number): New function.
(icalendar--get-weekday-abbrev) Use calendar-day-name-array.
(icalendar-export-region): Handle multi-line entries.
(icalendar--convert-ical-to-diary): Use calendar-day-name-array.