Smack currently does unnecessary escaping of XML text, where it
escapes e.g. '"' to '"'. This bloats the stanza size, especially
if JSON payloads are involved.
Fixes SMACK-892 (although there are probably still places where
XmlStringBuilder.escape() is used when XmlStringBuild.text() could
have been used).
replaces DefaultExtensionElement which is now deprecated.
Also changes Stanza (and MultiMap) API so that there can be duplicate extension
elements, as this change is required for StandardExtensionElement and by
the XMPP standard.
Florian Schmaus
Paul Schaub