Moved work_queue_worker to work_queue
Moved work_queue_{status, simulator} to work_queue.
Introducing libwork_queue.a

link with:
-lwork_queue -ldttools

Since libraries are static, this order is important.
Batch interface library

I had to pull the batch interface to its own library. work_queue_pool is
now also in the batch_interface directory.

Link with:

-ldtools_batch -lwork_queue -ldttools

Since libraries are static, this order is important.
Fixed wq linking of all cctools apps