hook up server-side kex-gex; add more documentation
group-exchange kex should work now on the server side. it will only be
advertised if a "moduli" file has been loaded (see the -gasp- docs) so we
don't spend hours (literally. hours.) computing primes. some of the logic
was previously wrong, too, since it had never been tested.
fixed repr() string for Transport/BaseTransport. moved is_authenticated to
Transport where it belongs.
added lots of documentation (but still only about 10% documented). lots of
methods were made private finally.