Authenticate (new) devices rather then login

[oliv3r]

To make logging in to new devices easier, it would be nice to be able to 'synchronize' a login via something as a QR code.

For me, I have a 32 char random password setup as my riot login, I did this via the web-app. Now I want to use the mobile app, and logging in is a pain. It would be nice if we could generate an auth token of some sort, that generates a QR code in the browser and allows me to scan this on the app, which lets me login afterwards.

This can be seen at work when linking the signal app to the signal-desktop app.