install requirements does not add Cython

[Ragnar-the-mighty]

The 1.9 release added Cython requirements but the install requirements does not list Cython so I get

9.684 File "/tmp/easy_install-m17cnkk1/ndindex-1.9/setup.py", line 10, in
9.684 .txt files include the exact pins, and are useful for deployments with
9.684 ModuleNotFoundError: No module named 'Cython'

[asmeurer]

Yeah, sorry about this. I messed up the release process and it didn't actually upload wheels. I am fixing it at #189 (should be done within the hour assuming nothing else goes wrong).

[asmeurer]

This should be fixed now. 1.9.1 has wheels for all platforms uploaded. Let me know if you encounter any further problems.

(and yes, I do need to update the docs, but that should only be necessary for development)