add sphinx

[alaniwi]

Add sphinx: http://sphinx-doc.org/install.html User requested. (Ticket 14056.)

[alaniwi]

Clean build in venv and import.

[alaniwi]

Clean build and import but running sphinx-build gives

The 'typing' distribution was not found and is required by Sphinx

[alaniwi]

Another runtime dependency:

pkg_resources.DistributionNotFound: The 'sphinxcontrib-websupport' distribution was not found and is required by Sphinx

[alaniwi]

And now imagesize

[alaniwi]

And now alabaster<0.8,>=0.7

[alaniwi]

And now babel!=2.0,>=1.3

[alaniwi]

And now snowballstemmer>=1.1.

Will find whole list of dependencies before continuing, to check if this is feasible, rather than fixing one by one.