work around existing instance not responding quickly

on a slow computer the first instance may have set up the local
server but not yet started the main loop, so when a user double clicks
on the icon twice, the second instance was timing out and opening
another window, then giving locked database errors

to work around this, increase the timeout, and tell the user the
existing instance is not responding instead of creating a new instance

https://anki.tenderapp.com/discussions/ankidesktop/30306-error
https://anki.tenderapp.com/discussions/ankidesktop/30550-im-sorry

aqt/__init__.py

@@ -157,7 +157,7 @@ class AnkiApp(QApplication):
     appMsg = pyqtSignal(str)
 
     KEY = "anki"+checksum(getpass.getuser())
-    TMOUT = 5000
+    TMOUT = 30000
 
     def __init__(self, argv):
         QApplication.__init__(self, argv)
@@ -191,7 +191,10 @@ class AnkiApp(QApplication):
         sock.write(txt.encode("utf8"))
         if not sock.waitForBytesWritten(self.TMOUT):
             # existing instance running but hung
-            return False
+            QMessageBox.warning(None, "Anki Already Running",
+                                 "If the existing instance of Anki is not responding, please close it using your task manager, or restart your computer.")
+
+            sys.exit(1)
         sock.disconnectFromServer()
         return True