router: refuse to send to empty JID, clarify identifiers
router: refuse to send to empty JID, clarify identifiers

samuelagm/ltx,ggozad/node-xmpp,WeBest/node-xmpp,xmppjs/xmpp.js,fritx/ltx,qbit/node-xmpp,agebrock/node-xmpp,xmppjs/xmpp.js,node-xmpp/node-xmpp,agebrock/node-xmpp,ggozad/node-xmpp,stliu/node-xmpp,tempbottle/node-xmpp,node-xmpp/ltx,eelcocramer/node-xmpp,fritx/ltx,node-xmpp/node-xmpp,bentaber/ltx,qbit/node-xmpp,swissmanu/ltx