Base: modernize C++11

* use nullptr

src/Base/Interpreter.h

@@ -116,14 +116,14 @@ protected:
     PyObject *_exceptionType;
 };
 
-inline Py::Object pyCall(PyObject *callable, PyObject *args=0) {
+inline Py::Object pyCall(PyObject *callable, PyObject *args=nullptr) {
     PyObject *result = PyObject_CallObject(callable, args);
     if(!result)
         throw Py::Exception();
     return Py::asObject(result);
 }
 
-inline Py::Object pyCallWithKeywords(PyObject *callable, PyObject *args, PyObject *kwds=0) {
+inline Py::Object pyCallWithKeywords(PyObject *callable, PyObject *args, PyObject *kwds=nullptr) {
     PyObject *result = PyObject_Call(callable, args, kwds);
     if(!result)
         throw Py::Exception();