Remove separate result set for Type requests.

Because results are now filtered by the tracker:available flag the
sparql query path is always used for type queries and
QGalleryTrackerResultSet is sufficient for those so take the opportunity
to shed some unneeded code.

Change-Id: Ib44dbcffeeaa2be8015ca6a727a45e19234f5782
Reviewed-by: Robin Burchell <robin+qt@viroteck.net>
Fix array overrun when new items are appended to a result set.

Check the correct iterator in the loop guard.

Change-Id: I1b6092febdc09ca908e9fab1716d98c3ebd6ec6f
Reviewed-by: Christopher Adams <chris.adams@jollamobile.com>