Fix clang compiler warnings:

+ fix -Winconsistent-missing-override
+ fix -Wunused-variable
+ fix -Wbraced-scalar-init
+ fix -Wparentheses (View3DInventorViewer::checkGroupOnTop: operator '?:' has lower precedence than '+'; '+' will be evaluated first)
+ fix -Wundefined-bool-conversion (MainWindow::updateActions)
+ suppress -Woverloaded-virtual but fix later

src/Gui/View3DInventorViewer.cpp

@@ -756,7 +756,7 @@ void View3DInventorViewer::checkGroupOnTop(const SelectionChanges &Reason) {
             SoSelectionElementAction action(node->getDetail()?
                     SoSelectionElementAction::Remove:SoSelectionElementAction::None,true);
             auto path = node->getPath();
-            SoTempPath tmpPath(2+path?path->getLength():0);
+            SoTempPath tmpPath(2 + (path ? path->getLength() : 0));
             tmpPath.ref();
             tmpPath.append(pcGroup);
             tmpPath.append(node);