[SofaPython] Restore the copy by default approach in toSofaParsableString

Because it breaks bckward compatibility and was not really better.

Author: damienmarchal

Plugin/src/SofaPython3/DataHelper.cpp

@@ -48,14 +48,14 @@ std::string toSofaParsableString(const py::handle& p)
     if(py::isinstance<py::str>(p))
         return py::str(p);
 
-    // Insure compatibility with data field code returning value instead of data.
+    // If the object is a data field we take its value to copy them.
     if(py::isinstance<sofa::core::objectmodel::BaseData>(p))
     {
         sofa::core::objectmodel::BaseData* data = py::cast<sofa::core::objectmodel::BaseData*>(p);
-        return data->getLinkPath();
+        return data->getValueString();
     }
 
-    // If the object is a numpy array we convert it to a list then to a sofa string
+    // If the object is a numpy array we convert it to a list then to a sofa string.
     if(py::isinstance<py::array>(p))
     {
         py::object o = p.attr("tolist")();