* Use resource loader embedding for better performance
(uses a slightly hacky method to achieve this, the only
alternative would be to fix the WikiEditor API, but that
would introduce a version dependency)
* Use SVGs from OOUI where available or create new ones where not.
These are used and available under the OOjs UI MIT licence.
* Provide PNG fallbacks using LESS mixin
* Remove unused icons
Change-Id: If38d51d24958716e2617c4cb515e7c0575cdfeba
