Minor bug fixes for test scripts
better support for using checksummed file timestamps as a higher resolution file timestamp
MAJOR Bug fix: Ancient race condition bug where Pipeline_run() and make_job_parameter_generator() relied on the GIL to use a set to synchronise two queues! Aargh. This was carefully masked by the 1 second delay between tasks so was probably never triggered... Now use Queue.queue to synchronize.
Queue.task_done() unnecessary unless join() is called