Part: modernize C++11

* use nullptr

src/Mod/Part/App/AttachExtensionPyImp.cpp

@@ -21,16 +21,16 @@ std::string AttachExtensionPy::representation(void) const
 PyObject* AttachExtensionPy::positionBySupport(PyObject *args)
 {
     if (!PyArg_ParseTuple(args, ""))
-        return 0;
+        return nullptr;
     bool bAttached = false;
     try{
         bAttached = this->getAttachExtensionPtr()->positionBySupport();
     } catch (Standard_Failure& e) {
         PyErr_SetString(PartExceptionOCCError, e.GetMessageString());
-        return NULL;
+        return nullptr;
     } catch (Base::Exception &e) {
         e.setPyException();
-        return NULL;
+        return nullptr;
     }
     return Py::new_reference_to(Py::Boolean(bAttached));
 }
@@ -39,16 +39,16 @@ PyObject* AttachExtensionPy::changeAttacherType(PyObject *args)
 {
     const char* typeName;
     if (!PyArg_ParseTuple(args, "s", &typeName))
-        return 0;
+        return nullptr;
     bool ret;
     try{
         ret = this->getAttachExtensionPtr()->changeAttacherType(typeName);
     } catch (Standard_Failure& e) {
         PyErr_SetString(PartExceptionOCCError, e.GetMessageString());
-        return NULL;
+        return nullptr;
     } catch (Base::Exception &e) {
         e.setPyException();
-        return NULL;
+        return nullptr;
     }
     return Py::new_reference_to(Py::Boolean(ret));
 }
@@ -74,7 +74,7 @@ Py::Object AttachExtensionPy::getAttacher(void) const
 
 PyObject *AttachExtensionPy::getCustomAttributes(const char* /*attr*/) const
 {
-    return 0;
+    return nullptr;
 }
 
 int AttachExtensionPy::setCustomAttributes(const char* /*attr*/, PyObject* /*obj*/)