add "known_hosts2john.py" utility for processing known_hosts file(s)
Bash completion: fix comletion for format classes

This was broken since --list=hidden-options included --costs=
and/or --bare-always-valid= options (both of them use mutliple
lines of text).
Merge pull request #688 from kholia/known_hosts2john

add "known_hosts2john.py" utility for processing known_hosts file(s)