Mostly the username is only used for the git committer or other display
purposes, and we can just fall back to a dummy value in these cases.
The only remaining place where an error is thrown is when starting local
pairing, which needs the username to be known.
When gpg.program is configured, it's used to get the command to run for
gpg. Useful on systems that have only a gpg2 command or want to use it
instead of the gpg command.
This fixes all instances of " \t" in the code base. Most common case
seems to be after a "where" line; probably vim copied the two space layout
of that line.
Done as a background task while listening to episode 2 of the Type Theory
podcast.
