DictionaryGrid should fire an edited event

Currently to detect when a field in a dictionary_grid has been edited, the programmer has to do this (in this case in a sub class, but self could be an instance as well:
        for c in self.get_columns():
            if type(c) == CheckColumn:
                c.renderer.connect("toggled",self._edited_toggled, c)
            else:
                c.renderer.connect("edited",self._edited, c)

And then they need to create a self._edited_toggled and a self._edited handler.

Dictionary grid should fire an edited event which delivers the necessary information to handle this in a single event and without connecting to the renderes.