#773 Display password / url / ... as QR code

[Ralf Hauser]

This will be useful if you have your WLAN key stored here and want a new user to get access without having her type every character, but just scan the password.

Similarly, an URL may be transferred this way to a device with a camera / QR-Reader

See for example https://threema.ch/en/blog for a generic text to QR conversion

see also #736