The custom theme is still needed for the version picker. Technically we
could add this HTML in the version-picker.js, but there's no guarantee
that the HTML IDs etc. wouldn't change out from under us.
We also no longer need the next/prev hiding plugin, as the original
point of it was to prevent those UI elements from interfering with our
custom TOC.
- Removed page summaries from CONTRIBUTING and installation pages as
this information was already in the table of contents on the right hand side
- Fixed some broken links in CONTRIBUTING
- Added margin-right tag for when table of contents is being shown
(otherwise the text in the page sometimes overlaps with it)
Andrew Morgan