TODO

[16-oct-09]
- Passing in something that will block instead of queue - eg
  a socket.  Does this make sense?
- Having several queues?  Would this have an effect or does it
  really matter?
[14-oct-09]
- How do we handle the issue of returning stuff?
  What's the best way for a thread in the thread pool to
  return its result if it needs to?
  Should we have a mechanism linking the thread that pushes
  the work item onto the pool and the result of this work item?
- dispatch(lambda) to become dispatch(lambda,arg1,arg2...)
- Move ThreadPool.rb into lib/ and create lib/threadpool for any 
  future .rb files
- Use Thread#[] to add properties like [:started] = Time.now etc
- Create a ThreadGroup within a ThreadPool instance and add all
  created threads to it.
  #add, #list what else?
- Have a response queue where threads from the pool can
  push a return object.
  The calling thread could wait on this queue.
- Get rid of the mutex in thread pool.
  Re-write live tests to use an independent mutex.
  Does it make sense to have tp.mutex ??
- ThreadPool.new(5,100) will create a threadpool with
  sized queue of 100 entries.
  Verify that the queue will block after 100