Tutorial documentation

More examples

It would be nice to have a tokenizer that used regular expressions
because it would be faster.

Teach the resolver about DNAME (right now it relies on the server adding
synthesized CNAMEs)

Add TKEY support.

TSIG works, but needs cleaning up -- probably better encapsulation of
TSIG state to make things much simpler and easier to use.

Pickling support.

