If the event was created by the MAPI client, the client's time zone (if
present) is assigned to the event's calendar in iCalEvent+MAPIStore.
This way, we can use it to deliver the event's properties correctly.
All-day and recurrent events have a binary property that describes the
time zone they take place in. We were using the user's time zone in
the webmail, but it may not be equal to the one in the client. This
difference eventually leads to time shifts in events.
This change adapts the bias fields in the TimeZoneStruct and TZRule
structures to the changes in openchange that allow this offsets to be
negative (zentyal/openchange bba372faea29d942b9471e6bed90bf425dc4b231)
Furthermore, [MS-OXOCAL] Section 2.2.1.41.1 indicates:
The wDay field is set to indicate
the occurrence of the day of the week within the month
(1 to 5, where 5 indicates the final occurrence during
the month if that day of the week does not occur 5 times).
[rule firstOccurrence] may return negative values according to iCal spec for
recurrent rules iCal 4.8.5.4 Recurrence Rule. For instance, for defining
a timezone whose recurrent rule is done using this rule:
RRULE:FREQ=YEARLY;BYMONTH=10;BYDAY=-1SU
This fixes the problem when editing a recurrent appointment in
Outlook were incorrectly shifted when SOGo provides back the event.
