* scribo/toolchain/internal/text_in_picture_functor.hh
	(text_in_picture_functor<I>::get_factor): New precondition: ensure
	argument `max_dim_size', used as denominator, is non null.
	(text_in_picture_functor<I>::operator()): Do not resize the image
	if `max_dim_size' is null.
	Some cosmetic changes.