* core/concept/link_functor.hh: New concept.

	* core/internal/link_functor_base.hh: New Base class for link
	functor.

	* primitive/link/compute.hh,
	* primitive/link/compute_several.hh,
	* primitive/link/internal/anchors_3.hh,
	* primitive/link/internal/find_link.hh,
	* primitive/link/internal/find_several_links.hh,
	* primitive/link/with_several_right_closest_links.hh,
	* primitive/link/with_several_right_links_overlap.hh,
	* primitive/link/with_single_left_link_dmax_ratio.hh,
	* primitive/link/with_single_right_link_bottom.hh,
	* primitive/link/with_single_right_link_dmax_ratio.hh,
	* primitive/link/with_single_right_link_top.hh: New routines.

	* primitive/link/internal/link_center_dmax_base.hh,
	* primitive/link/internal/link_center_dmax_ratio_base.hh,
	* primitive/link/internal/link_functor_base.hh,
	* primitive/link/internal/link_ms_dmax_base.hh,
	* primitive/link/internal/link_ms_dmax_ratio_base.hh: New functors.

	* primitive/link/with_several_left_links.hh,
	* primitive/link/with_several_right_links.hh: Use the new routines.

	* primitive/link/with_single_left_link.hh,
	* primitive/link/with_single_right_link.hh: Revamp and use the new
	routines.

git-svn-id: https://svn.lrde.epita.fr/svn/oln/trunk@4705 4aad255d-cdde-0310-9447-f3009e2ae8c0