* scribo/binarization/internal/compute_sauvola_threshold.hh:
	New. Move sauvola_threshold related routines here.

	* scribo/binarization/internal/first_pass_functor.hh,
	* scribo/binarization/sauvola.hh,
	* scribo/binarization/sauvola_ms.hh,
	* scribo/binarization/sauvola_threshold_image.hh: Move debug
	variables...

	* scribo/binarization/internal/sauvola_debug.hh: ... here. New.

	* scribo/binarization/sauvola_threshold_image_debug.hh: Remove.

	* src/binarization/Makefile.am,
	* src/binarization/sauvola_debug.cc,
	* src/binarization/sauvola_ms_debug.cc: Improve debug outputs.

	* src/binarization/pgm_sauvola_threshold_image.cc: New.