--Complete restructuring of the-force code to use BARRIERs with pthreads.
--Still a couple of bugs to work out on autodrive.
--I think I have the barrier code working correctly, although I'm getting '**BAD LINE' occurring in my imu-log.txt occasionally.  Not sure where that is coming from, since I can't find that text anywhere in my code.
--I found one bug in the way that I was pulling data from the encoders--the encoders were reporting a dt of 20ms, regardless of how long it had really been since the last data had been sent.  I fixed that in the encoders' Arduino code and got the rover to drive a simulated straight forward 1m and stop.  I was getting some pretty huge (>100ms) dt's between encoder readings, but it seemed to work ok.
--Then I figured that there was a similar bug in the IMU Arduino code and tried to fix it in the same way.  I must have broken something in doing that, since now the-force will fire up, take a path, start the cameras, and then do nothing.  I need to spend some more time troubleshooting it.