* scribo/debug/alignment_decision_image.hh
	(alignment_decision_image)
	* scribo/debug/bboxes_enlarged_image.hh (bboxes_enlarged_image)
	* scribo/debug/decision_image.hh (decision_image)
	* scribo/debug/links_decision_image.hh (links_decision_image)
	* scribo/debug/links_image.hh (links_image)
	* scribo/debug/looks_like_a_text_line_image.hh
	(looks_like_a_text_line_image):
	Fix the type of the value to be returned by theses functions.