Start work on search feature.

Work in progress.  Search box and autocompletion for talents and talent types are
implemented, but autocompletion for classes is missing, and the box doesn't
actually do anything yet.

Specific changes:
- Add typeahead.js.
- talent_spoilers.lua now creates search indexes.
- Reorganize main.css; try to better separate site-wide styles from per-page.
- Move updateNav to versions module, since it's only used to implement that
  module.
Talent search is minimally functional
Updates to styles and search logic
Try improving styling.

Fix duplicate ids.
Bugfixes

Sustain stamina was not reported. Talent category links from classes page
weren't working.
Redesign sticky header logic.

New logic removes the need to clone the header, which is necessary now that
we're adding features like search box that would be hard to keep in sync.
Class searches
Updates to to-do list
Merge branch 'master' of https://github.com/tometips/tometips
Merge branch 'search'