* headers.mk: add new headers to distribution.

	* mln/io/all.hh: include new headers.

	* mln/io/cloud/all.hh,
	* mln/io/cloud/load.hh,
	* mln/io/cloud/save.hh: load and save a cloud of points.

	* tests/unit_test/Makefile.am,
	* tests/unit_test/mln_io_cloud_load.cc,
	* tests/unit_test/mln_io_cloud_save.cc: add new unit tests.

git-svn-id: https://svn.lrde.epita.fr/svn/oln/trunk@3240 4aad255d-cdde-0310-9447-f3009e2ae8c0