Dropping support for 2.7 in 2020

[François Boulogne]

> It's just that I trust us more to produce
> these releases than big institutions to make their systems evolve! 
:)


To add a little piece to the thoughts shared on this question, we may
wonder if there was or there is or there will be soon a feature to
implement that would cause a lot of pain to make it work with python 2.7.

We may also wonder if for those users who need to use old systems, will
it be possible to install scikitimage if we constantly increase the
minimal version of our dependencies (cython etc). If they are not also
available on their system, it means that in practice, they will need to
stuck on an older version of scikit-image anyway.

I never learned python2, but I don't know the nice features of python3
only because I can't contribute with them. That's sad.


-- 
François Boulogne.
http://www.sciunto.org
GPG: 32D5F22F