add support for the iCalendar fields "CREATED" and "LAST-MODIFIED"

[sweber83]

This adds the fields CREATED and LAST-MODIFIED to events.

[antoinerousseau]

Hi guys,
I realize that when I'm feeding my output to Google Calendar, if some events are modified, Google does not take the modifications into account. I think that when the UID does not change, and the event has no "modified" date, it ignores the content.
Thus, what's up with this PR? Can I help? :)
Cheers!

Edit: I realize it's part of the 3.0 roadmap \o/

[sebbo2002]

Edit: I realize it's part of the 3.0 roadmap \o/

Yep, it is. Feel free update this pull request (or create a new one) to build this feature for the 3.0 version. It's already in develop.

[antoinerousseau]

OK! Also, I'm wondering if maybe I should increment the SEQUENCE when updating events.
https://tools.ietf.org/html/rfc5546#section-4.2.3

[sebbo2002]

You can do so, see the docs. But I don't know if that's enough for Google Calendar as I don't use it…

[sebbo2002]

There is a more up-to-date PR available: #75
Close it for now…