delete maze gen code that was copied from Wikipedia
delete maze gen code that was copied from Wikipedia

Credit was given but should have been more explicit at the top-level
of the source tree, given different ("share-alike") license terms.
Anyway, keeping the code is not well motivated because there is
already a similar function, random_world().

tulip-control/tulip-control,tulip-control/tulip-control,tulip-control/tulip-control,tulip-control/tulip-control