* libnautilus-extensions/nautilus-lib-self-check-functions.h:
	Add hook for scalable fonts test which im going to add soon.

	* libnautilus-extensions/nautilus-scalable-font.h:
	* libnautilus-extensions/nautilus-scalable-font.c:
	(nautilus_scalable_font_text_width), New convenience function to
	measure just the text width.
	(nautilus_self_check_scalable_font): Add hook for scalable fonts
	test which im going to add soon.