Added cleaner benchmark (and condition variable).

Also added boost queue for benchmark comparison (#beat boost). Info:
MPMC Queue Benchmark

Boost Queue
      Enqueues (8x100000): 124ms
      Dequeues (8x100000): 84ms
      Fair mpmc (~1000000 items, 4 enq, 4 deq): 592ms
      Enqueue-weighted mpmc (~1000000 items, 6 enq, 2 deq): 393ms
      Dequeue-weighted mpmc (~1000000 items, 2 enq, 6 deq): 1024ms

Shared Queue
       Enqueues (8x100000): 112ms
       Dequeues (8x100000): 893ms
       Fair mpmc (~1000000 items, 4 enq, 4 deq): 157ms
       Enqueue-weighted mpmc (~1000000 items, 6 enq, 2 deq): 176ms
       Dequeue-weighted mpmc (~1000000 items, 2 enq, 6 deq): 133ms