Some options are now automatically configured by the version 1.20:
- project
- html_last_updated_fmt
- latex_engine
- latex_elements
- version
- release
Note that we don't actually drop 'project' since it's referenced
elsewhere in the file and cleaning that up would be hassle.
Change-Id: Ibe4add5a9391c3b3bc49206c9ac65721cedddf5a
39923ae345