* tests/core/p_array.cc: Add iteration test.
	* mln/core/internal/site_iterator_base.hh: New; based upon...
	* mln/core/internal/pseudo_site_base.hh: ...this.
	* mln/core/internal/pseudo_site_base.hh
	(subject, q_subject): New; factor those definitions.
	* mln/core/p_array_piter.hh (p_array_fwd_piter_): Update.
	(p_array_bkd_piter_): Deactivate.
	* mln/core/p_array.hh
	(p_array): Change into constant proxy; move defs into guards.
	(to_site): Delete mutable version.
	(change_target): New.
	* mln/core/concept/site_iterator.hh (operator site): Remove;
	that was obsolete code.


git-svn-id: https://svn.lrde.epita.fr/svn/oln/branches/cleanup-2008@1972 4aad255d-cdde-0310-9447-f3009e2ae8c0