Switch to using an enum with registration for icon sizes, instead of

Switch to using an enum with registration for icon sizes, instead of

2001-03-12  Havoc Pennington  <hp@redhat.com>

	* gtk/gtkiconfactory.h, gtk/gtkiconfactory.c: Switch to using an
	enum with registration for icon sizes, instead of strings.

	* gtkimage.h, gtkimage.c, gtkstyle.h, gtkstyle.c, gtkwidget.h,
	gtkwidget.c: Fix to reflect GtkIconSize