* mln/core/p_complex_piter.hh (mln::p_complex_bkd_piter_<D, P>):
	(operator<<(std::ostream&, const p_complex_bkd_piter_<D, P>&)):
	New.
	(mln::p_complex_fwd_piter_<D, P>::next_): Reimplement to make it
	symmetric to mln::p_complex_bkd_piter_<D, P>::next_.
	* mln/core/p_complex.hh (mln::p_complex<D, P>::bkd_piter): Set
	typedef to p_complex_bkd_piter_<D, P>.
	* mln/core/p_complex_piter.hh: Test the backward iterator on
	complex_image.


git-svn-id: https://svn.lrde.epita.fr/svn/oln/trunk@2148 4aad255d-cdde-0310-9447-f3009e2ae8c0