Xpra: Ticket #2521: more useful window title

On many systems the hostname will be left as "localhost", so when showing "xterm on localhost" or "xterm on localhost.localdomain" we're not really providing helpful information to the end user.

Thu, 19 Dec 2019 08:35:42 GMT - Antoine Martin: status changed; resolution set

Done in r24769.

Sat, 23 Jan 2021 05:53:32 GMT - migration script:

this ticket has been moved to: https://github.com/Xpra-org/xpra/issues/2521