for some reason Nifty is built with python2 but better_apidoc.py is executed with python 3 in the CI; therefore it does not find the nifty library to generate it's documentation; so now testing run with python2 on both sides

Using better-apidoc to generate templated package and module documentation; added generation templates

documentation genaration setup in CI, testing commented to speedup verification of docs on commit, will uncomment at merge

Notebook demo

See merge request ift/NIFTy!217