All Sites: Clean up footer styles

Ref gh-295
All Sites: Consolidate footer links

Ref gh-295
All Sites: Add license and GitHub links in footer

Closes gh-295
3.1.13
qunitjs.com: Add download link style to inputs

Ref jquery/qunitjs.com#62
Closes gh-296
3.1.14
All Sites: Use natural sorting for terms

Fixes gh-268
Closes gh-298
Header: Update event navigation
3.1.15
Header: Fix Chicago conference link
3.1.16
Header: Remove jQueryTO event link

Closes gh-299
3.1.17
CSS: Add note class

Ref jquery/api.jqueryui.com#199
3.1.18
learn.jquery.com: Cleanup
learn.jquery.com: Move prev/next links above contributors

Line endings were changed from Windows to Unix, so `-w` is needed for a
sane diff.

Fixes jquery/learn.jquery.com#474
3.1.19
UI: Fix link (as Manning's affiliate program is broke indefinitely).
3.1.20