[QOrganizerItemMemoryEngineData] Get rid of unused member

Change-Id: I7fcad310b16da6dc694f58b9b845e4ca5e0ff12f
Reviewed-by: Michael Krasnyk <michael.krasnyk@gmail.com>
Reviewed-by: Robin Burchell <robin+qt@viroteck.net>
[QOrganizerItemMemoryEngineData] Get rid of extra ref counter

QOrganizerItemMemoryEngineData is a QSharedData successor
and thus already ref-counted; simply use existing counter.

Change-Id: I2c6f34215dd1149d33cbccfd8e85288f5e5ec241
Reviewed-by: Robin Burchell <robin+qt@viroteck.net>
[QOrganizerItemMemoryEngine] Don't keep anonymous store in hash

This solves a possible issue when "id" parameter value equals to
some existing anonymous store's UUID.

Change-Id: I5608310f02674e6b2e54512cc5c6c06a3ff94aba
Reviewed-by: Robin Burchell <robin+qt@viroteck.net>
[QOrganizerItemMemoryEngine] Fix collection change notifications

Since the backend could share the data across instances,
all instances that share changed data must be notified
(do exactly the same as for QOrganizerItemChangeSet).

Change-Id: Iff50b8f0c8b67ed102128ff0a64854c3856aa7f3
Reviewed-by: Robin Burchell <robin+qt@viroteck.net>
[QOrganizerItemMemoryEngine] Decrease code duplication

Change-Id: I6d5430b75fe09c335c92d253d56a27940dc7af15
Reviewed-by: Michael Krasnyk <michael.krasnyk@gmail.com>
Reviewed-by: Robin Burchell <robin+qt@viroteck.net>