Refactor the xml descriptor classes into separate module
Don’t collect addrinfo into list
Introduce pre_handshake coroutine for CertificateVerifiers
Replace pbkdf2 implementation with the one provided by python3.4

If it is available. Otherwise, we use our own (which is btw about 10
times slower).
Introduce default timeout for IQ requests and such
Fix AttributeError (initialize Client._xmlstream to None)
Allow stay_connected() to take over an established connection
Print some debug timing for SCRAM
Remove even preliminary DANE support
Fix NameErrors / AttributeErrors in sasl module on auth failure
Implement name check on certificates, using ssl.match_hostname
Fix NameError in PKIXCertificateVerifier