Make destructors of all generated Py class protected

This is to avoid to create an object on the stack and thus to clutter Python's reference counting mechanism

src/Mod/Path/App/AreaPyImp.cpp

@@ -203,10 +203,12 @@ std::string AreaPy::representation(void) const
 
 PyObject *AreaPy::PyMake(struct _typeobject *, PyObject *args, PyObject *kwd)  // Python wrapper
 {
-    std::unique_ptr<AreaPy> ret(new AreaPy(new Area));
-    if(!ret->setParams(args,kwd))
+    AreaPy* ret = new AreaPy(new Area);
+    if(!ret->setParams(args,kwd)) {
+        Py_DecRef(ret);
         return 0;
-    return ret.release();
+    }
+    return ret;
 }
 
 // constructor method

src/Tools/generateTemplates/templateClassPyExport.py

@@ -56,6 +56,9 @@ namespace @self.export.Namespace@
  */
 class @self.export.Namespace@Export @self.export.Name@ : public @self.export.FatherNamespace@::@self.export.Father@
 {
+protected:
+    ~@self.export.Name@();
+
 public:
     static PyTypeObject   Type;
     static PyMethodDef    Methods[];
@@ -76,8 +79,7 @@ public:
     @self.export.Name@(@self.export.TwinPointer@ *pcObject, PyTypeObject *T = &Type);
     static PyObject *PyMake(struct _typeobject *, PyObject *, PyObject *);
     virtual int PyInit(PyObject* args, PyObject*k);
-    ~@self.export.Name@();
-    
+
 + if (self.export.Initialization):
     int initialization();
     int finalization();