Anchor.js 1.0.0 drops the need to use anchor.css, so we remove it
from the codebase and move any leftover styles over to docs.css.

Closes #16488 by merging it.

This reverts commit 229e8889.

ZeroClipboard v2.x drops IE < 9 support.

[ci skip]

Fixes #16269.
Closes #16301 by merging a rebased version of it.

Fixes #14245

Refs #14409

Refs #14409

Fixes #14038.

Research supporting this choice of approach:
    https://gist.github.com/cvrebert/68659d0333a578d75372

Why not <button>?
Even with a `tabindex` attribute, they don't gain focus when clicked upon in:
    * Mac OS X Firefox 30.0
    * Mac OS X Safari 7.0.5

Refactor navs: new classes, remove separate pills & tabs files, drop justified nav because it never really worked

[skip sauce] [skip validator]

.bs-docs-navbar class doesn't seem to be used anywhere at all

Also use the official filenames.