* mln/morpho/attribute/count_adjacent_vertices.hh,
	* mln/morpho/closing/area_on_vertices.hh,
	* mln/morpho/opening/area_on_vertices.hh:
	  Make area_on_vertices work with new algebraic code, and
	adapt count_adjacent_vertices accumulator as a morpho attribute.

	* mln/morpho/closing_area_on_vertices.hh,
	* mln/morpho/closing_attribute.hh,
	* mln/morpho/opening_area_on_vertices.hh,
	* mln/morpho/opening_attribute.hh:
	  Delete old implementations.

	* tests/morpho/artificial_line_graph_image_wst.cc,
	* tests/morpho/lena_line_graph_image_wst2.cc:
	  Update test files using area_on_vertices.

git-svn-id: https://svn.lrde.epita.fr/svn/oln/trunk@3451 4aad255d-cdde-0310-9447-f3009e2ae8c0