Add GraphView.clone and Node.clone to binding.

Should solve #100 (closed)

python_binding/graph/pybind_GraphView.cpp

@@ -114,7 +114,7 @@ void init_GraphView(py::module& m) {
           :return: Whether any replacement has been made.
           :rtype: bool
           )mydelimiter")
-
+          .def("clone", &GraphView::clone)
           .def("get_nodes", &GraphView::getNodes)
           .def("get_node", &GraphView::getNode, py::arg("node_name"))
           .def("forward_dims", &GraphView::forwardDims, py::arg("dims")=std::vector<std::vector<DimSize_t>>())