Tags: patch

I've been steadily working on this and I've reached another milestone
this week: I now have a working implementation of recurrence rules,
including time zone support. This is the big, complicated part of
iCalendar semantics that none of the existing code completely supports;
but it's essential, because most date-times in iCalendar are defined as
local times with a reference to a time zone, and calculating an actual
UTC offset requires applying the recurrence rules for that time zone.
Updated patch attached; the main addition here is icalendar-recur.el,
plus supporting functions in icalendar-macs.el and icalendar-utils.el.

It was a *lot* more work to get this working than I expected (mostly
because time zones are complicated...who knew? ;), but I can at least
say now that all the examples in RFC5545 work; see the tests in
icalendar-recur-tests.el.