194 multi threading

This addresses #194: 
 * multi-threaded Pyro daemon, 
 * continuous request handling in a background thread, 
 * batched job submission in a background worker thread.

Not for merge to master yet (some tidying to do...) but can be demoed - *Dave's Evil Load Test* (now held in ```dev/suites/dave```) runs like dream on this branch. No major problems apparent at this stage.