Used Data Forms for extension of In-Band Registration as required by XEP-0077 § 4.
+Added "defined condition" elements in error stanzas as required by RFC 6120 § 8.3.2.
+Changed type of "invalid-token" error to "modify".
+If the server supports and is ready to perform Pre-Authenticated IBR, it MUST add a <token> element to the response (TODO: 'token' or 'preauth'?):
-