Implements an Add-on Loader so that other add-ons, such as the FFZ Add-on Pack, can be loaded directly by FFZ without requiring the user to install multiple extensions into their browser.
* Added: Notify users when a new build of FrankerFaceZ is available.
* Fixed: The option to disable channel hosting. (Revert to previous channel hosting data scheme from 21 days ago.)
* Configure the project to allow the use of JSX in .jsx files.
* Add linting for JSX.
* Rewrite most existing code that uses `createElement` to use JSX syntax.
* Stop importing `createElement as e`. That's what the minifier is for. And we don't have to write it manually so much now because of JSX syntax.