Fixed a bug where the DynamixelUSB was hanging on shutdown. I tracked this down to the fact that two threads were trying to write to the controller at the same time. So I had to harden the shutdown code. I added code to pause the IO before doing any of the shutdown code and then wait until a IOPaused signal. This seems to have fixed the problem.
Added printing of any error communications from USB2Dynamixel on synch move command.