Dont print stanzas of received duplicates to the log

https://xmpp.org/extensions/inbox/eme.html

A Body is added with an info message, if there is
a resource online that doesnt support OMEMO

Commit 9d7306001 introduced a syntax error by including a line break in the
description.

this package doesnt play well with demandimport
it hast to be importet at start