lattice polytope nfacets method broken for non-reflexive polytopes

[mhampton]

In the nfacets method, for non-reflexive lattice polytopes this is computed from:

self._nfacets = len(self._facet_normals)

but self._facet_normals is a matrix, which does not have a len method. So I think this should instead be

self._nfacets = self._facet_normals.nrows()

A doctest should also be added for this case.

[novoselt]

This is actually fixed by this patch (which needs a review):

​http://trac.sagemath.org/sage_trac/ticket/6778

[mhampton]

OK, sorry about that. I am working through your tickets and I should have looked more closely. This ticket can be closed as a duplicate of 6778.

-Marshall