Ticket #253 (defect)

The start/end is floating which produces a period for the first instance which does not match the period for the master event - the event crosses a dst boundary. Causes a non-unique exception on save as the recurrence ids are the same. The recurrence ids are the UTC time of the instance start (before override) so we need to use either event or instance but not both.

BEGIN:VCALENDAR PRODID:-//Ben Fortuna//iCal4j 1.0//EN VERSION:2.0 CALSCALE:GREGORIAN BEGIN:VEVENT DTSTAMP:20070822T212913Z SUMMARY:British Summer Time Ends DESCRIPTION: TRANSP:OPAQUE CLASS: UID:0a66b927-814b-49dd-973c-28a4dd7e78c9 DTSTART:20021027T000000 DTEND:20021027T235959 RRULE:FREQ=YEARLY;INTERVAL=1;BYMONTH=10;BYDAY=SU;BYSETPOS=-1 END:VEVENT END:VCALENDAR