This patch completely replaces the previous versions of our notebook patch
(gtk-hamann_jeske-980130-0 / gtk-hamann_jeske-980211-0).

New in this patch :

- notebook now supplies a popup menu for fast page switching
- added gtk_notebook_{prepend|insert|append}_page_menu.
 These functions have an extra parameter GtkWidget *menu_label,
 which is used as popup menuitem
- testgtk notebook sample has been changed accordingly

The patch is against the cvs - tree.