[idn] automagic case-insensitive comparisons in the DNS server

["Adam M. Costello" <amc@cs.berkeley.edu>]

I just had a wacky idea relevant to the schemes that store ACE at
the DNS servers.  It's possible to encode the case of the Unicode
characters as the case of the ACE characters.  Since DNS servers
already do case-insensitive comparisons of ASCII host names, they would
automagically be doing case-insensitive comparisons of international
host names.

Here's how it could work:  Instead of base-32, the ACE uses base-24:  8
letters for 0000 through 0111 and 16 letters for 10000 through 11111,
for an average of 4.5 bits per character instead of 5.  (Notice that
there is still exactly one way to encode an arbitrary bit string.)  The
Unicode characters are all converted to lower case (or all upper case),
but the intended case of each Unicode character is indicated by the case
of whichever ACE character contains its first bit (or last bit).

This doesn't help with other kinds of insensitivities you might want in
the comparisons, so it might be better to go with a general solution,
but I thought this was cute and worth throwing out there.

AMC