* mln/world/binary_2d/subsample.hh
	(world::binary_2d::subsample(const image2d<bool>&, unsigned)):
	Properly initialize (and deallocate) the sliding window (array of
	pointers).
	Fix the size of	the output image.
	Have the declaration of this function match its definition.
	* tests/world/binary_2d/subsample.cc: New test.
	* tests/world/binary_2d/Makefile.am
	(check_PROGRAMS): Add subsample.
	(MOSTLYCLEANFILES): Add subsample-small.pgm.