Support XEP-0198 revision 3
Reported by orivej:
nbxmpp and consequently Gajim support only the second revision of the XEP-0198 protocol, and can not enable stream management with servers that support only the third and latest revision (released in the specification version 1.2 in 2011).
Some changes are summarized in the specification revision history [1], but the main change seems to be that sent stanzas count begins ticking on the client after it sends \, and on the server after it sends \, rather than from the beginning of the session.