* Use `aria-selected` instead of `aria-expanded`
* Change tab.js to use `aria-selected` rather than `aria-expanded`
* Add `aria-orientation=vertical` to vertical tab list
* Remove dynamic tabs with dropdowns
* Fix non-interactive code examples
* Only set `aria-selected` on the `role="tab"` trigger - this stops `aria-selected` being incorrectly added to the `role="tabpanel"` itself (probably harmless, but nonetheless incorrect)

* fix(scrollspy): Handle nested navs when nav-link inside nav-item

* [scrolspy] Find only child .nav-link's inside .nav-item

* [scrollspyt] Add tests for nested navs with nav-link inside nav-item

* fix troy-o's in test

* use .babelrc.js, compile bundled/non-bundled with loose mode

* add back helper, exclude typeof transform

Album example: fix holder.js calls

to fix the images

Structure examples with appropriate `<main>`, `<header>`, `<footer>`

Fix(docs): duplicate class in navbar docs

Remove not necessary condition in tooltip.js

v4 Collapse.js: Accordions with text-truncate causes the page to jump on close

This new section will replace the `hidden-*` class. https://v4-alpha.getbootstrap.com/layout/responsive-utilities/

More info can be found here at https://getbootstrap.com/docs/4.0/migration/#responsive-utilities