Cleanup, and further improvements to concurrency. ...

Should hopefully be bullet proof now.  Seems to handle the stress test
OK.  The tutor client doesn't lose sync during stress test, so hopefully
that problem is now fixed.

Whole bunch of stuff: ...

- Refactored the map panels to separate the queue label into its own panel.
 - Made queue label overflow without resizing the panels that contain it.
 - Fixed some threading issues by making expanding a couple of synchronized blocks into full method syncs.
 - Added some more constants for things (version number, exit codes).
 - Show message dialog when the server can't be found.
 - Added a test class that causes a message flood for testing threading and queue overflow.

Improved TutorClient. Huge refactor. Icon now read from classpath/jar.