Maybe a stack trace can tell us more about our mysterious error.

git-svn-id: svn+ssh://src.earth.threerings.net/narya/trunk@4638 542714f4-19e9-0310-aa3c-eee0fc999fb1

src/as/com/threerings/presents/client/Communicator.as

@@ -285,6 +285,7 @@ public class Communicator
 
         // total failure
         Log.getLog(this).warning("socket error: " + event);
+        Log.dumpStack();
         shutdown(new Error("socket closed unexpectedly."));
     }