Pickle cached value of volume and f-vector

[gh-kliem]

Volume, f-vector and Ehrhart polynomial of polyhedra can be hard to compute, but take little memory when saving.

So we pickle those values, e.g.

+    @cached_method(do_pickle=True)
-    @cached_method
     def f_vector(self):

[gh-kliem]

New commits:

​f28363d	pickle cache of volume, f_vector, ehrhart polynomial
​cd13c82	typo

[gh-LaisRast]

It looks good to me. Is there a reason why you did not do the same for functions of CombinatorialPolyhedron??

[gh-kliem]

Yes, CombinatorialPolyhedron doesn't exactly pickle. It just reduces, i.e. save enough data to initialize the object again. At some point one could think about a better way of pickling, of course.