* mln/topo/is_simple_2d.hh: New.
	* mln/morpho/skeleton_constrained.hh: New.
	* tests/morpho/skeleton_constrained.cc: New.
	* tests/morpho/Makefile.am: Update.
	* img/small.pbm: New.
	* img/fly.pbm: New.
	* mln/win/multiple_size.hh (i_): Change type to signed.
	(size_): Change return type to int to prevent warning.
	(is_valid_, invalidate_): Fix the case of the iterator
	construction is deferred.


git-svn-id: https://svn.lrde.epita.fr/svn/oln/branches/cleanup-2008@2896 4aad255d-cdde-0310-9447-f3009e2ae8c0