Path: modernize C++11

* use nullptr

src/Mod/Path/App/CommandPyImp.cpp

@@ -71,9 +71,9 @@ PyObject *CommandPy::PyMake(struct _typeobject *, PyObject *, PyObject *)  // Py
 // constructor method
 int CommandPy::PyInit(PyObject* args, PyObject* kwd)
 {
-    PyObject *parameters = NULL;
+    PyObject *parameters = nullptr;
     char *name = "";
-    static char *kwlist[] = {"name", "parameters", NULL};
+    static char *kwlist[] = {"name", "parameters", nullptr};
     if ( PyArg_ParseTupleAndKeywords(args, kwd, "|sO!", kwlist, &name, &PyDict_Type, &parameters) ) {
         std::string sname(name);
         boost::to_upper(sname);
@@ -204,7 +204,7 @@ PyObject* CommandPy::toGCode(PyObject *args)
 
 PyObject* CommandPy::setFromGCode(PyObject *args)
 {
-    char *pstr=0;
+    char *pstr=nullptr;
     if (PyArg_ParseTuple(args, "s", &pstr)) {
         std::string gcode(pstr);
         try {
@@ -267,7 +267,7 @@ PyObject *CommandPy::getCustomAttributes(const char* attr) const
             return Py_None;
         }
     }
-    return 0;
+    return nullptr;
 }
 
 int CommandPy::setCustomAttributes(const char* attr, PyObject* obj)