Change CometPlugin so it re-uses stuff from RealtimePlugin

plugins/Comet/cometupdate.js

@@ -0,0 +1,30 @@
+// update the local timeline from a Comet server
+//
+
+var CometUpdate = function()
+{
+     var _server;
+     var _timeline;
+     var _userid;
+     var _replyurl;
+     var _favorurl;
+     var _deleteurl;
+     var _cometd;
+
+     return {
+          init: function(server, timeline, userid, replyurl, favorurl, deleteurl)
+          {
+               _cometd = $.cometd; // Uses the default Comet object
+               _cometd.init(server);
+               _server = server;
+               _timeline = timeline;
+               _userid = userid;
+               _favorurl = favorurl;
+               _replyurl = replyurl;
+               _deleteurl = deleteurl;
+               _cometd.subscribe(timeline, RealtimeUpdater.receive);
+               $(window).unload(leave);
+          }
+     }
+}();
+