* Add focus trap util
* Add focus trap to Modals
Fixes#2663
* Split tab press into `onTab` handler
* Remove deprecated code
* Use requestAnimationFrame instead of setTimeout
* Reduce code duplication
* Implement focus trap in nav drawer
Fixes#2665
* Hide drawer when window is resized to be bigger
Fixes issue where focus trap would remain on the drawer when it is
just the app header, if the drawer was opened then the window was
made larger.
* Simplify conditional function calls
* Fix modal focus trap
* Remove debug code
* Simplify resize handler conditional statements
* Add info about reasoning of resize handler
* Prefer native JS methods over jQuery
* Update conditional function call to handle `undefined`
* Expose screen sizes as CSS custom properties
* Use `window.matchMedia` rather than resize handler
* Fix spelling error
Co-authored-by: David Sevilla Martin <me@datitisev.me>
* Remove breaking change
Co-authored-by: David Sevilla Martin <me@datitisev.me>
* Replace gulp with webpack and npm scripts for JS compilation
* Set up Travis CI to commit compiled JS
* Restructure `js` directory; only one instance of npm, forum/admin are "submodules"
* Refactor JS initializers into Application subclasses
* Maintain partial compatibility API (importing from absolute paths) for extensions
* Remove minification responsibility from PHP asset compiler
* Restructure `less` directory
