QTableGenerator: replace a call to a member function with direct element access

Saves one copy of a vector.

Change-Id: I3a14c46e306c3d44a64c6e0d8cd2f120b2c208d7
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
Update QOffscreenSurface docs regarding threads

Change-Id: Ic2e3230835aa7fc1b1c3ac0530a65cd478e1ec5f
Reviewed-by: Gunnar Sletta <gunnar@sletta.org>