Close an open message base after just 10 seconds of client inactivity

... and log a debug-level log message when doing so.

The current input/receive timeout duration (5 minutes) might be a bit long to
leave a message base open (though, there's no known issue with doing so). For
example, when users read message bases using the terminal server, they can sit
for much longer than 5 minutes reading an open message base.