* gladeui/glade-popup.c: Allow adding new actions to action groups from the palette ("Add widget here").

	* plugins/gtk+/glade-accels.[ch]: Moved individual accelerator [de]serialization here, special integration
	  for action types, for actions only show one accelerator and dont load/save the "activate" signal name.

	* plugins/gtk+/glade-gtk.c, plugins/gtk+/gtk+.xml.in: Added support for GtkActionGroup <--> GtkAction
	  relationships and support for editing/loading/saving of accelerators which can be associated with
	  actions inside an action group.