Also change StringUtils.escapeForXML() and Packet.toXML() to return
CharSequence instead of String. XmlStringBuilder now has 'optX' methods.
Remove XmlUtils in favor of XmlStringBuilder
Also remove the Exceptions from the signature of getRoster().
Extend ConnectionListener with connected() and authenticated()
callbacks, required by Roster to be notified so that the Roster can be
loaded *after* login.
Change all \r\n into unix style newlines. Add missing newlines at the
end of a file and activate the newline checkstyle module, that enforces
'\n' as newline and a newline at the end of every file.