* apps/generic-skel/image2d-skel-unconstrained.cc,
	* apps/generic-skel/image2d-skel-with-end-points.cc,
	* apps/generic-skel/image3d-skel-unconstrained.cc,
	* apps/mesh-segm-skel/mesh-complex-max-curv-1-collapse.cc,
	* apps/mesh-segm-skel/mesh-complex-max-curv-2-collapse.cc,
	* apps/mesh-segm-skel/mesh-complex-pinv-curv-skel.cc:
	Display the size of the input.
	Time the thinning step.
	* milena/apps/generic-skel/test-mixed.in,
	* milena/apps/mesh-segm-skel/test-mixed.in:
	New.
	* apps/generic-skel/Makefile.am (generated_tests): Add test-mixed.
	(test-mixed): New target.
	(check-mixed): New (phony) target.
	* apps/mesh-segm-skel/Makefile.am: Likewise.
	($(generated_tests)): New target.
	(AM_CPPFLAGS): Add -I$(top_builddir)/milena so that
	mln/version.hh, which is a generated header, can be found by the
	compiler.