- in lnurl.py, make request methods async
- in Qt GUI, lnurl network requests no longer block the GUI thread
- but they still do in the kivy GUI
- "lightning address" (LUD-16) support is removed for now as the
email addresses are indistinguishable from openalias email addresses
(both protocols should have added and enforced a prefix, or similar,
to remove this kind of ambiguity -- now we would need to make a
network request just to identify what kind of ID we were given)