* mln/canvas/browsing/depth_first_search.hh: update and add more doc.

	* mln/graph/attribute/card.hh,
	* mln/graph/attribute/representative.hh,
	* mln/graph/compute.hh: enable the possibility of computing data on a
	graph.

	* tests/Makefile.am,
	* tests/graph/Makefile.am,
	* tests/graph/attribute/Makefile.am,
	* tests/graph/attribute/card.cc,
	* tests/graph/attribute/representative.cc: add new tests.

git-svn-id: https://svn.lrde.epita.fr/svn/oln/trunk@3670 4aad255d-cdde-0310-9447-f3009e2ae8c0