We add a new theme config so the theme can say it supports font-awesome.
If this is true, the pix_icon renderer will call a mapping function to map
from the moodle style t/edit to a font-awesome style fa-cog icon name. Then the renderer
will either render an image tag for old icons - or an accessible font-awesome <i> tag.
This mostly works - but there are some places where we don't use the pix icon renderer, and
we directly create image tags with pix_url image sources. These will need updating (Atto icons,
drag and drop move icons, editpdf icons).
The videojs javascript is over 1MB of javascript which we don't need to
load on every page, now that we only require it demand, the js can be
lazily loaded when its needed, which keeps the first.js smaller and more
likely to stay in browser cache.
The previously used minification libraries were:
a) Unmaintained
b) Had some silly licensing issues (MDL-36457)
The new library is smaller, maintained, active and GPL-compatible.
No changes from the upstream version have been made, it is recommended by
upstream to install these depdencies via composer - but the composer
installation is bundled with a load of test files, shell scripts etc (and
we don't use composer to manage 'production dependencies') so we have to
do it manually.
