v0.1.30-pre.72

preview: you can hand somebody a link to one message. A message's actions carry Copy link
just under Copy text, on the phone, the desktop and the web, and opening the link lands on
that chat at that message with it lit up. A message link carries no group name on purpose,
so somebody who is not in the group sees the group's short id and the ordinary offer to
ask to join. No schema change.