ICal recurrence support

[adamfranco]

Hello All,

These three commits improve support for recurrence in iCal feeds by allowing multi-day weekly recurrence and by allowing for exceptions to event recurrence. Lastly, there is a fix that make UNTIL limits work correctly.

If you would like to see this support in action, our Library Hours calendar in Google Calendar makes use of both multi-day weekly recurrence and exceptions to the normal recurrence schedule:

• http://www.google.com/calendar/embed?src=middlebury.edu_ol2e145ahtv7tga6qavgcoretc@group.calendar.google.com&ctz=America/New_York&mode=week
• http://www.google.com/calendar/ical/middlebury.edu_ol2e145ahtv7tga6qavgcoretc@group.calendar.google.com/public/basic.ics

Let me know if there are any modifications needed.

Best, Adam

[akinspe]

Thank you so much for this. I will be analyzing it further and hopefully merging it in next week.