title: QFileDialog that accepts a single file or a single directory
body: <p>Is it possible to show a QFileDialog where the user can select a file or a directory, either one? </p>
  
  <p><code>QFileDialog::getOpenFileName()</code> accepts only files, while <code>QFileDialog::getExistingDirectory()</code> is directories-only, but I need to show a file dialog that can accept both a file or a directory (it makes sense for my program). <code>QFileDialog::​Options</code> didn't have anything promising.</p>