Improve the trait system.
	
	* mln/core/category.hh: New.
	* mln/core/concept/image.hh,
	* mln/core/concept/function.hh,
	* mln/core/concept/meta_accumulator.hh,
	* mln/core/concept/value_set.hh,
	* mln/core/concept/weighted_window.hh,
	* mln/core/concept/browsing.hh,
	* mln/core/concept/dpoint.hh,
	* mln/core/concept/point_set.hh,
	* mln/core/concept/object.hh,
	* mln/core/concept/neighborhood.hh,
	* mln/core/concept/window.hh,
	* mln/core/concept/value.hh,
	* mln/core/concept/point_site.hh,
	* mln/core/concept/accumulator.hh (category): New.
	* mln/trait/solve.hh: New.
	* mln/core/trait/op_plus.hh: Rename as...
	* mln/trait/op_plus.hh: ...this.
	Update.
	* mln/core/trait/promote.hh: Rename as...
	* mln/trait/promote.hh: ...this.
	Update.
	* mln/core/trait/all.hh: Update.
	* mln/trait/all.hh: New.
	* mln/trait/op_minus.hh: New.
	* mln/trait/op_uminus.hh: New.
	* mln/trait/op_times.hh: New.
	* tests/trait_op_plus.cc: New.
	* mln/metal/binary_arith_trait.hh: Remove; obsolete.
	* mln/value/props.hh: Update.
	(vec, mat): Move to the file they belong to.

	
	Then use it.

	* mln/core/ops.hh,
	* mln/metal/mat.hh,
	* mln/metal/vec.hh,
	* mln/value/int_s.hh,
	* mln/value/int_u.hh: Use traits.
	Update.
	* mln/arith/plus.hh: Add code to be activated.

	
	Disambiguation.
	
	* mln/trait/images.hh (fixme): Rename as...
	(fixme_): ...this to avoid conflict with mln::internal::fixme.
	* mln/pw/image.hh: Update.
	* mln/border/mirror.hh,
	* mln/border/resize.hh,
	* mln/core/dpoints_piter.hh,
	* mln/core/image1d_b.hh,
	* mln/core/image2d_b.hh,
	* mln/core/image3d_b.hh,
	* mln/core/pset_if.hh,
	* mln/core/pset_if_piter.hh: Fully name fixme.
	* mln/border/fill.hh (fixme): Remove include.

	
	Misc.
	
	* mln/border/duplicate.hh: Fix typo.
	* mln/metal/mat.hh (operator*=): Fix sig.
	Fix params order.
	* mln/value/rgb.hh (min, max): Remove, cause meaningless.
	(operator-, operator+): Likewise.
	(card_): Set to 0.


git-svn-id: https://svn.lrde.epita.fr/svn/oln/trunk@1215 4aad255d-cdde-0310-9447-f3009e2ae8c0