Reduce tab stop in script editor to something sane

src/unsupportedserial.w

 	deviceSettingsModel(new SaltModel(2)),
 	scriptEditor(new QTextEdit)
 {
+	scriptEditor->setTabStopWidth(20);
 	QVBoxLayout *dummyLayout = new QVBoxLayout;
 	QTabWidget *central = new QTabWidget;
 	QWidget *deviceConfigurationWidget = new QWidget;