distribute polytope.intersect to Polytope.intersect and Region.intersect
distribute polytope.intersect to Polytope.intersect and Region.intersect

to make the code clear and object-oriented and reduce the likelihood of bugs there.
Polytope.intersect now accepts only Polytope arguments.
Region.intersect accepts any iterable container of Polytopes.

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