This module processes iCalendar (vCalendar 2.0) files as specified
in RFC 2445 into a data structure.  It handles recurrences (`RRULE's),
exclusions (`EXDATE's), event updates (events with a `RECURRENCE-ID'),
and nested data structures (`ATTENDEES' and `VALARM's).  It currently
ignores the `VTIMEZONE', `VJOURNAL' and `VFREEBUSY' entry types.
