changes Application to send to broadcast data using user.send as opposed
to _server.sendBroadcastMessage so that it checks whether the user is interested.

renames _sendBroadcastMessage to _sendToAllUsers
changes time between keepalives to 15s to avoid filling up websocket log
adds /challenges to default interesting urls for User
removes move.setPreviousItem/setNextItem etc from colview History widget
adds getNode() to colview Fullmove widget