A few alterations made.
* Added timing code to print the number of Micro Seconds taken from start to finish (bar the PPM printing).
* Identified a possible problem with the deque implementation where re-allocation might occur concurrently with a top access. This could cause a seg-fault and needs to be fixed using the top
  mutex for the deque.
* Work is now distributed equally to each thread. This makes it easier to compare with a non-load balanced version of the code.