* mln/accu/count_value.hh: Fix doc.

	* mln/convert/from_to.hxx,
	* mln/value/int_u.hh,
	* mln/value/qt/rgb32.hhL: Add new from_to overloads.

	* mln/convert/to_qimage.hh: Add a missing include.

	* mln/convert/to_qimage_nocopy.hh: Rename an overload.

	* mln/core/concept/function.hh: Add new concept n2v.

	* mln/geom/rotate.hh: rename center() to pcenter().

	* mln/histo/compute.hh: Fix a namespace ambiguity.

	* mln/io/magick/save.hh: Handle qt::rgb32.

	* mln/io/plot/save.hh: Add an overload for histograms.

	* mln/labeling/relabel.hh: Make 'nlabels' const.

	* mln/topo/skeleton/crest.hh: Fix a bug.

	* tests/core/other/box_runstart_piter.cc: Write a valid test.