Generate reference documentation with Sphinx

[ddemidov]

This adds sphinx configuration, so that refence documentation could be generated automatically. I've registered my own fork on the readthedocs site, so that you have an idea of how the generated doc would look like:

http://ev3dev-lang-python-1.readthedocs.org/en/latest/

Once this is merged, I'll register the main repo there. It may be setup to rebuild the documentation automatically after each commit pushed to github.

[rhempel]

Would be nice if commands was a bullet list or at least one per line

[rhempel]

Thanks!