[Cython] Hashability of Python memoryviews

Hi,

there's a ticket on the CPython bug tracker where correct hashability of
the "memoryview" type is being discussed. I don't have an opinion on it,
but some of you might. It could translate into a similar feature for
Cython's array and memory view types (no idea if hashability has been
considered there yet).

http://bugs.python.org/issue15814

Stefan