* mln/core/macros.hh (mln_bkd_pixter_): New macro.
	* mln/core/internal/pixel_iterator_base.hh
	(mln::pixel_iterator_base_<I, E>::start)
	(mln::pixel_iterator_base_<I, E>::invalidate)
	(mln::pixel_iterator_base_<I, E>::is_valid):
	Remove methods.
	(mln::forward_pixel_iterator_base_<I, E>)
	(mln::backward_pixel_iterator_base_<I, E>):
	New classes.
	* mln/core/pixter1d.hh
	(mln::fwd_pixter1d<I>): Inherit from
	mln::internal::forward_pixel_iterator_base_.
	(mln::bkd_pixter1d<I>): New class.
	* mln/core/pixter2d.hh
	(mln::fwd_pixter2d<I>): Inherit from
	mln::internal::forward_pixel_iterator_base_.
	(mln::bkd_pixter2d<I>): Inherit from
	mln::internal::backward_pixel_iterator_base_.
	(mln::bkd_pixter2d<I>::start): Remove method.
	(mln::fwd_pixter2d<I>::fwd_pixter2d)
	(mln::bkd_pixter2d<I>::bkd_pixter2d):
	Use initialization lists instead of assignments.
	* mln/core/pixter3d.hh
	(mln::fwd_pixter3d<I>): Inherit from
	mln::internal::forward_pixel_iterator_base_.
	(mln::bkd_pixter3d<I>): New class.
	* mln/core/p_image2d_pixter.hh
	(mln::p_image2d_fwd_pixter<P>): Inherit from
	mln::internal::forward_pixel_iterator_base_.
	(mln::p_image2d_bkd_pixter<P>): Inherit from
	mln::internal::backward_pixel_iterator_base_.
	* mln/core/image1d.hh (mln::trait::bkd_pixter< image1d<T> >::ret):
	Set to bkd_pixter1d< const image1d<T> >.
	* mln/core/image2d.hh: Add FIXMEs.
	* mln/core/image3d.hh (mln::trait::bkd_pixter< image3d<T> >::ret):
	Set to bkd_pixter3d< const image3d<T> >.
	* tests/core/pixter1d.cc, tests/core/pixter2d.cc:
	New tests.
	* tests/core/image3d.cc: Rename as...
	* tests/core/pixter3d.cc: ...this.
	Exercise bkd_pixter3d.
	* tests/core/Makefile.am (check_PROGRAMS): Remove image3d.
	Add pixter1d, pixter2d and pixter3d.
	(image3d_SOURCES): Remove.
	(pixter1d_SOURCES, pixter2d_SOURCES, pixter3d_SOURCES): New.


git-svn-id: https://svn.lrde.epita.fr/svn/oln/trunk@1911 4aad255d-cdde-0310-9447-f3009e2ae8c0