[TD]assorted Preference updates

- section line convention label
- remove superfluous save/restore on changeEvent
- change default scrub count
- add preference for default symbol dir
- add preference for display of section cut line

src/Mod/TechDraw/Gui/DlgPrefsTechDrawAdvancedImp.cpp

@@ -84,9 +84,7 @@ void DlgPrefsTechDrawAdvancedImp::loadSettings()
 void DlgPrefsTechDrawAdvancedImp::changeEvent(QEvent *e)
 {
     if (e->type() == QEvent::LanguageChange) {
-        saveSettings();
         ui->retranslateUi(this);
-        loadSettings();
     }
     else {
         QWidget::changeEvent(e);