QSettings: use QStandardPaths to get XDG_CONFIG_HOME.

This allows to use the "test mode" of QStandardPaths in unittests,
to stay away from the user's real settings.

Change-Id: I1cb1f63a4bff35dfe236924c4dcd7cf761ee50c1
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@digia.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
tst_qfiledialog: use QStandardPaths test mode

Otherwise, when interrupting the test half-way (e.g. in gdb),
the user's ~/.config/QtProject.conf would be modified.

Change-Id: Id582c4a3fbf0acbed460126fccf0d39b3a09758a
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
QInputDialog: simplify signalForMember()

Instead of playing clever tricks with the index variable, simply
scan through the list of argument-carrying signals and, if nothing
fits there, fall explicitly back to accepted().

Change-Id: I1be49ce601edb854cc1bab5be994b2c09fe31b3c
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>