Fix image_if related-classes.
	
	* mln/core/image_if.hh,
	* mln/core/internal/image_if_base.hh,
	* mln/core/image_if_value.hh: Fix.
	* mln/labeling/estimate.hh: Update.
	* tests/image_if_value.cc: New.

	Make float01[_] work on float!
	
	* mln/value/float01_.hh,
	* mln/value/float01.hh: Fix.

	
	Enhance the trait solver mechanism; now it can rely
	on category inheritance :-)
	
	* 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/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: Specialize the category flag.
	(super): New in those specializations.

	
	Update.
	
	* tests/trait_op_uminus.cc: New.
	* tests/core_category.cc: New.
	* tests/trait_op_plus.cc: Augment.
	* mln/trait/op_plus.hh (set_binary_): Set category.
	* mln/trait/promote.hh: Likewise.
	* mln/trait/op_uminus.hh: Likewise.
	* mln/trait/solve.hh: Augment.
	* mln/trait/all.hh: Typo.
	* mln/core/category.hh (Unknown<void>): New.
	(Built_In): Move into...
	* mln/value/builtin.hh: ...this new file.
	* mln/core/ops.hh: Include builtin.hh.


	Misc.

	* mln/core/internal/exact.hh: Remove useless param.
	* mln/value/graylevel.hh: Fix.


git-svn-id: https://svn.lrde.epita.fr/svn/oln/trunk@1222 4aad255d-cdde-0310-9447-f3009e2ae8c0