Show text up to next structural character, whitespace, or quote
character instead of just the first character.
Forgotten quotes now get reported like "Stray 'command'" instead of
"Stray 'c'".
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20190914153506.2151-9-armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>