add QScopedPointerDeleteLater, a custom deleter for QObjects

This is a custom deleter for QObjects that are participating in an event
loop (e.g. waiting for signals to complete a task), which need to be
deleted using deleteLater() rather than just delete.

Change-Id: I3084ea28a6829a299c7400006c617fc23cf15160
Reviewed-by: J-P Nurmi <jpnurmi@digia.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
QMessageBox - add detailed text to manual test

Even though detailed text does not work that well, it should still
be in the manual test.

Change-Id: I051f9f0592ad9206dc42f0e9929c1be32baec832
Reviewed-by: J-P Nurmi <jpnurmi@digia.com>