Tabs: SCSS fixes and improvments
-Fixed the figcaption not being clickable in carousel style 2
-Added placeholders
Menu: Fixed header text of mobile menu (fixes #3982)
Merge pull request #3992 from pjackson28/fixmobilemenuheader

Menu: Fixed header text of mobile menu (fixes #3982)
Toggle: fix WAI-ARIA with `summary` element as accordion tab
Merge pull request #3988 from patheard/toggle-wai-aria

Toggle: fix WAI-ARIA with `summary` element as accordion tab
Toggle: add plugin unit tests
Tab: remove placeholder unit test
Merge pull request #3991 from LaurentGoderre/carrousel-scss-fix

Tabs: SCSS fixes and improvments
Merge pull request #3997 from patheard/toggle-unit-test

Unit tests: toggle and tabbed interface
Menu: Fixed several issues with the mobile menu and optimized the code (fixes #3982, #3983, #3984 and #3986)
Merge pull request #3998 from pjackson28/fixmobilepanel

Menu: Fixed several issues with the mobile menu and optimized the code (fixes #3982, #3983, #3984 and #3986)
Helpers: Added missing true parameter to distinguish between focusable and discoverable
Merge pull request #4000 from pjackson28/fixfocusablehelper

Helpers: Added missing true parameter to distinguish between focusable and discoverable
Share: output sprite and SCSS inside plug-in dir
Tabs: Inline filter mixins
Menu: Move demo assets
Menu: Remove unrelated data-ajax from demos
Index: Fixed HTML5 markup issues and adjusted code indentation in HBS files.
Merge pull request #4003 from EricDunsworth/v4.0-index-html5-validation

Index: Fixed HTML5 markup issues and adjusted code indentation in HBS fi...
Merge pull request #4004 from nschonni/v4-menu-demo-cleanup

V4 menu demo cleanup