[Cython] 0.16.1

[mark florisson]

Ok, so for the bugfix release 0.16.1 I propose that everyone cherry
picks over its own fixes into the release branch (at least Stefan,
since your fixes pertain to your newly merged branches and sometimes
to the master branch itself). This branch should not be merged back
into master, and any additional fixes should go into master and be
picked over to release.

Some things that should still be fixed:
    - nonechecks for memoryviews
    - memoryview documentation
    - more?

We can then shortly-ish after release 0.17 with actual features (and
new bugs, lets call those features too), depending on how many bugs
are still found in 0.16.1.