Sketcher: [skip ci] Fix several clazy issues:

* Missing reference in range-for with non trivial type [-Wclazy-range-loop-reference]
* Unused QString [-Wclazy-unused-non-trivial-variable]
* Missing emit keyword on signal call [-Wclazy-incorrect-emit]
* Don't call QList::operator[]() on temporary [-Wclazy-detaching-temporary]
* Use multi-arg instead [-Wclazy-qstring-arg]
* Maybe you meant to call ViewProvider2DObjectGrid::onChanged() instead [-Wclazy-skipped-base-method]

src/Mod/Sketcher/Gui/ViewProviderPython.cpp

@@ -56,7 +56,7 @@ void ViewProviderCustom::onChanged(const App::Property* prop)
             }
         }
     }
-    PartGui::ViewProviderPart::onChanged(prop);
+    ViewProviderSketch::onChanged(prop);
 }
 
 void ViewProviderCustom::updateData(const App::Property* prop)