Make sure we have a good random seed on the default RNG, that the
predictable RNG is clearly marked as such, that random strings are
actually the length requested, and that they contain a restricted set of
characters only.
"Inspired" by https://github.com/BenLubar/Rnoadm/maybetls
but avoids pulling the whole game as a dependency, and has the API slightly changed,
as it makes no sense to have non-tcp TLS listeners.
New node ID:s contain four Luhn check digits and are grouped
differently. Code uses NodeID type instead of string, so it's formatted
homogenously everywhere.
