Reordering of the attendees should not be a signitifcant change

[floerke]

If a server (using sabre) receives a VEVENT update it will send mails to all attendees. Not for all modified events, but for events with a "significant change". The calculation of "signifcant change" is done by vobject.

I have trouble with to many "Invitation: ..."-Mails for events that has not been changed.

Investigating this I have seen:

• the events were modified by the client and sent to the server (eg. to save the acknowledgment of an alarm).
• the client has changed the order (not the attendees itself) of the attendees in the modified event
• vobject calculated a "significant change"
• the server sent the email

I think everything is correct, except, the reordering is not a significant change. Why the client desires to reorder the attendees? I don't know, but I think this should not be a significant change.

[phil-davis]

Fixed by #541