Use the KEditToolBar(KXMLGUIFactory* factory) constructor from kxmlguiwindow too, so that any kxmlguiclients that have been added to the mainwindow, will show up in the toolbar editor.

This happened with Stephen Kelly's kxmlguieditor guiclient, for instance.

Fix the way KXmlGuiWindow reconstructs the GUI after toolbar config has changed, so that it doesn't lose child guiclients.

IOW, this is simply a bit more of KParts technology moving up to kdeui, for lightweight components to work too.