implement the GtkCellLayout interface, drop packing/attribute/cell data

implement the GtkCellLayout interface, drop packing/attribute/cell data

Wed Oct  1 22:43:40 2003  Kristian Rietveld  <kris@gtk.org>

	* gtk/gtkcellview.[ch]: implement the GtkCellLayout interface, drop
	packing/attribute/cell data functions from the header,
	(gtk_cell_view_set_cell_data): added support for cell data funcs.

	* gtk/gtkcombobox.[ch]: implement the GtkCellLayout interface, drop
	packing/attribute/cell data functions from the header, implemented
	cell data func support.

	* gtk/gtkcomboboxentry.c (gtk_combo_box_entry_new): updated
	for the move to GtkCellLayout.

	* tests/testcombo.c (create_combo_box_grid_demo), (main): ditto.