QStandardPaths: ensure that paths use '/' on all platforms, as the comment said

Change-Id: Id70b5e92c07f63e71e7a1a8fb229f927d352ebdd
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
QStandardPaths: remove trailing slash when reading from user-dirs.dirs

For consistency with all other sources of paths, which do not return
a trailing slash, as tested by the unittest. This avoids double slashes
in paths, after apps append something to the path.

Change-Id: Iabcde11eee27df0b185780e2b655fbbb02ed63b5
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
QPA fix: allow setting the initially selected name filter (KDE)

In KDE, without this patch, the Q_ASSERT in the following code fragment
fails:

QFileDialog dialog;
QStringList list = QStringList() << "c (*.cpp)" << "h (*.h)";
dialog.setNameFilters(list);

QString filter("h (*.h)");
dialog.selectNameFilter(filter);

dialog.show();
Q_ASSERT(dialog.selectedNameFilter() == filter);

The reason for the fail is that the selectNameFilter() does not properly
propagate the filter to the QPA plugin. So the first part of this patch
adds d->options->setInitiallySelectedNameFilter(filter); in the function
QFileDialog::selectNameFilter().

The second part of this patch makes sure that the initially set name
filter in the QFileDialogOptions "options" is not overwritten in the
helperPrepareShow() function. This is achieved by adding an if(),
following the if() for the initiallySelectedfiles() the line below.

With this patch, the Q_ASSERT() holds true in KDE Framework 5's
file dialog integration.

Change-Id: I15d8c88a0fa3cdc03e3330f3458bbad139a71212
Reviewed-by: Kevin Ottens <kevin.ottens@kdab.com>
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
Reviewed-by: Shawn Rutledge <shawn.rutledge@digia.com>