Gui: modernize some classes

src/Gui/PythonWrapper.cpp

@@ -154,7 +154,7 @@ PythonToCppFunc toCppPointerCheckFuncQuantity(PyObject* obj)
     if (PyObject_TypeCheck(obj, &(Base::QuantityPy::Type)))
         return toCppPointerConvFuncQuantity;
     else
-        return 0;
+        return nullptr;
 }
 
 void BaseQuantity_PythonToCpp_QVariant(PyObject* pyIn, void* cppOut)
@@ -167,7 +167,7 @@ PythonToCppFunc isBaseQuantity_PythonToCpp_QVariantConvertible(PyObject* obj)
 {
     if (PyObject_TypeCheck(obj, &(Base::QuantityPy::Type)))
         return BaseQuantity_PythonToCpp_QVariant;
-    return 0;
+    return nullptr;
 }
 
 #if defined (HAVE_PYSIDE)
@@ -360,7 +360,7 @@ QObject* PythonWrapper::toQObject(const Py::Object& pyobject)
     return reinterpret_cast<QObject*>(ptr);
 #endif
 
-    return 0;
+    return nullptr;
 }
 
 QGraphicsItem* PythonWrapper::toQGraphicsItem(PyObject* pyPtr)
@@ -413,7 +413,7 @@ QIcon *PythonWrapper::toQIcon(PyObject *pyobj)
 #else
     Q_UNUSED(pyobj);
 #endif
-    return 0;
+    return nullptr;
 }
 
 Py::Object PythonWrapper::fromQDir(const QDir& dir)