* mln/core/concept/proxy.hxx: Add and reorder forward
	declarations.
	* mln/accu/site_set/rectangularity.hh (rectangularity<P>): Do not
	re-import base class attributes as protected members, so that the
	base class can still access them.
	Adjust.
	* mln/geom/seeds2tiling_roundness.hh,
	* mln/subsampling/antialiased.hh,
	* mln/world/inter_pixel/dim2/make_edge_image.hh:
	Add missing header inclusions.
	* mln/io/plot/save.hh (save)
	* mln/morpho/tree/propagate_node.hh
	(propagate_node_to_descendants):
	Do not provide default arguments twice.
	* mln/topo/face_iter.hh,
	* mln/topo/n_face_iter.hh:
	Add `this->' qualifiers to disambiguate calls to base class
	methods.
	* tests/metal/converts_to.cc (from_2): Do not rely on
	uninitialized data.
	(main): Add a test case.