*  mln/core/concept/image.hpp,
*  mln/core/concept/object.hpp,
*  mln/core/domain/box.hpp,
*  mln/core/domain/box_iter.hpp,
*  mln/core/image/internal/nested_loop_iterator.hpp,
*  mln/core/image/ndimage.hpp,
*  mln/core/image/ndimage_iter.hpp,
*  mln/core/image/ndimage_pixel.hpp,
*  mln/core/image/ndimage_pixel_iterator.hpp,
*  mln/core/image_base.hpp,
*  mln/core/iterator/iterator_base.hpp,
*  tests/bench_iterator.cpp: New style iterator.

* mln/core/concept/check.hpp,
* mln/core/concept/image.hpp: Set check method in its own file.
* mln/core/concept/iterator.hpp: new style iterator concept
* mln/core/image/internal/nested_loop_iterator.hpp: New style iterator
* mln/core/iterator/iterator_base.hpp: Facade for iterators.
* mln/core/range/iterator_range.hpp: Util to build range from iterator.

  * mln/core/image/internal/nested_loop_iterator.hpp: Small fix.
  * mln/core/image/image_expr.hpp,
  * mln/core/image/image_ops.hpp,
  * mln/core/image_base.hpp,
  * mln/core/iterator/transform_pixel_iterator.hpp,
  * mln/core/ops.hpp: New

Iterator factorization, ndimage iterator uses nested_loop_iterator.
Add some specific functions to image2d.

	* mln/core/ndimage.hpp,
	* mln/core/ndimage.i,
	* mln/core/ndimage_iter.hpp,
	* mln/core/ndimage_pixel.hpp,
	* mln/core/ndimage_pixel_iterator.hpp: Move to...
	* mln/core/image/ndimage.hpp,
	* mln/core/image/ndimage_iter.hpp,
	* mln/core/image/ndimage_pixel.hpp,
	* mln/core/image/ndimage_pixel_iterator.hpp.
	* mln/core/image/image2d.hpp : New
	* mln/core/image/internal/nested_loop_iterator.hpp:  New