Save window state to self.settings.

def saveSettings(self):
        """Save window state to self.settings."""
        self.settings.beginGroup('mainwindow')
        self.settings.setValue('geometry', self.saveGeometry())
        self.settings.setValue('windowstate', self.saveState())
        self.settings.setValue('path_to_ramp_file', self.path_to_ramp_file)
        self.settings.setValue('path_to_load_mot_file',
                               self.path_to_load_mot_file)
        self.settings.endGroup()