* Render attachments inside iframes.
* Fix up the image and video views
* Fix m.audio
* Comments, and only use the cross domain renderer if the attachment is encrypted
* Fix whitespace
* Don't decrypt file attachments immediately
* Use https://usercontent.riot.im/v1.html by default
* Put the config in the React context.
Use it in MFileBody to configure the cross origin renderer URL.
* Call it appConfig in the context
* Return the promises so they don't get dropped