Fix several clazy issue:

* Missing reference in range-for with non trivial type [-Wclazy-range-loop-reference]

src/Gui/SplitView3DInventor.cpp

@@ -502,7 +502,7 @@ Py::Object AbstractSplitViewPy::getattr(const char * attr)
     if (name == "__dict__" || name == "__class__") {
         Py::Dict dict_self(BaseType::getattr("__dict__"));
         Py::Dict dict_base(base.getattr("__dict__"));
-        for (auto it : dict_base) {
+        for (const auto& it : dict_base) {
             dict_self.setItem(it.first, it.second);
         }
         return dict_self;