* src/Makefile.am: added files glade-base-editor.[ch]

	* src/glade-accumulators.[ch]: new accumulators
	  glade_string_accumulator() and glade_stop_emission_accumulator ()

	* src/glade-app.c, src/glade-project.c and src/glade-command.c:
	  use of GladeWidgetClass toplevel flag.

	* src/glade-gtk.c: Use of GladeBaseEditor for GtkMenuBar, GtkToolBar
	  and GtkMenu editors.

	* src/glade-marshallers.list: added OBJECT:OBJECT,UINT
	  BOOLEAN:OBJECT,UINT BOOLEAN:OBJECT,OBJECT and STRING:OBJECT

	* src/glade-property.[ch]: Added old_value parameter to GladeProject
	  "value_changed" signal.

	* src/glade-widget-class.[ch]: added toplevel flag to GladeWidgetClass

	* src/glade.h: added GLADE_XML_TAG_TOPLEVEL

	* src/glade-base-editor.[ch]: Created GladeBaseEditor class from
	  GtkMenuBarEditor code from glade-gtk.c

	* widgets/gtk+.xml.in:
	  o added launch-editor-function for GtkToolbar and GtkMenu.
	  o Set GtkTextView post-create-function to empty (we do not need a
	    placeholder in it).
	  o Set toplevel="True" in GtkWindow and GtkMenu.

	* doc/widgetclasses.sgml: added toplevel property docs

	* po/POTFILES.in: added src/glade-base-editor.c