Documentation additions.

Documentation additions.

        * gtk/gtkoldeditable.c, gtk/gtkrc.c,
        gtk/gtkstyle.c: Documentation additions.

        * gtk/gtkmenu.c (gtk_menu_set_accel_path),
        gtk/gtkmenuitem.c (gtk_menu_item_set_accel_path),
        gtk/gtkwidget.c (gtk_widget_add_accelerator): Typo and markup fixes.

        * gtk/gtkitemfactory.c (gtk_item_factory_add_foreign): Document.

        * gtk/gtkaccelmap.c (gtk_accel_map_add_filter): Explain intended use.

        * gtk/running.sgml: Add ids to some elements to make them
        addressable as link targets.