[idn] Simple change of hostname characters

[Dan <Dan.Oscarsson@trab.se>]

There has been a lot of talk about "just use UTF-8" or not.

Once the hostname was restricted to A-Z,0-9 and -, and it was
not allowed to start with a digit.
This was later changed so that it was allowed to start with a digit
and not to end with a hyphen.
Of some reason it is still allowed to have more than one hyphen
in a row, even though that does not fit with names.

To allow the use UTF-8 one have to change the allowed characters to:

A-Z,0-9,-,codes 128-255.

As long as programs allow those byte codes and does not change them, all
programs can handle hostnames with UTF-8 in them. Does this changing result in
more difficulties than the change in allowed hyphens and digits did?

   Dan