Url import

[heinrichmartin]

Allow pasting the unit's URL (instead of scanning the QR-code). This is the reverse use case of #42, but it is way less important than that one.

[heinrichmartin]

Maybe this issue gains importance as a workaround for #60.

While revisiting this issue, I was considering whether the ideal implementation registers the app for opening URLs (of a relevant pattern). However, distributing URLs by email/text message increases the risk that it is forwarded/shared. I still think that it is a benefit to not require QR codes, but the warning "do not share" must be prominent when sending out URLs - and the QR code should remain the most convenient way.