Bug 1091722 - Remove requirements.txt; r=glandium

requirements.txt isn't being used by the documentation infrastructure.
We nuke it.

--HG--
extra : rebase_source : d53ee5c329790d0ed7d75d6d9f451269dda6c485
Bug 1091722 - Use Read The Docs theme for Sphinx; r=glandium

Read the Docs has a lovely Sphinx theme that beats the pants off the
built-in and default theme. And since it looks like MDN's Sphinx theme
is dead in the water, this gets us a nice UI win until the MDN theme
comes back from the dead.

--HG--
extra : rebase_source : b4f92cf8263843d3118a85a7d9b59b98d5dd0613
Bug 1091722 - Don't require configure before generating docs; r=glandium

Ever since Sphinx variable reading operates at the AST level (bug
1071012), we don't technically need a fully configured environment in
order to generate the documentation!

This patch stubs out the config environment object with a fake one that
provides the only needed context to generate the Sphinx docs. This
allows us to build the Sphinx docs on a fresh clone of the tree with no
configure and with no object directory.

--HG--
extra : rebase_source : f44513f01706391a5932a20c1437fcc8697611cd