Add a new child.
Add a new child, possibly dummy, depending on the implementation, of a internal keeping. When the child is effectively added the event Efl.Model.child,added is then raised and the new child is kept along with other children.
Since 1.23
child_add @pure_virtual { return: Efl.Object; }
Efl_Object *efl_model_child_add(Eo *obj);