* doc/tutorial/tutorial.tex: Add more contacts.

	* mln/accu/label_used.hh: Do not use label<>::next().

	* mln/draw/line.hh: Add a fixme.

	* mln/io/dump/save.hh: Close the file.

	* mln/io/plot/save.hh: Fix an invalid prototype.

	* mln/io/pnm/load.hh: Fix an invalid static check.

	* mln/io/raw/get_header.hh: Fix comment.

	* mln/labeling/pack.hh: Disable a static check on symbolic values.

	* mln/math/diff_abs.hh: Add a fixme.

	* mln/world/inter_pixel/full2image.hh: Use mln_concrete().

	* mln/data/fill_with_value.hh,
	* mln/io/raw/load.hh,
	* mln/io/raw/save.hh,
	* mln/labeling/compute.hh,
	* mln/registration/icp.hh: Aesthetic changes.