Provide Python 3.7 wheels on PyPi

[robbmcleod]

It would be handy if binary wheels were provided on PyPi:

https://pypi.org/project/mkl-fft/#history

I understand that mlk-fft is available through conda, but that can become a bit of a dependency-matching mess to deal with. Installation through PyPi is a lot cleaner and easier to manage, in my experience.