title: gpars withExistingPool
body: <p>I am trying to use gpars <code>GParsPool.withExistingPool</code> in gpars 0.12
  It expects a <code>jsr166y.ForkJoinPool</code> but looks like in the jsr166y jar I have, there is no way to create that class(?). The only ones I can create are <code>jsr166y.forkjoin.ForkJoinPool</code> like so:</p>
  
  <pre><code>FJPool fjPool = new FJPool(2);
  jsr166y.forkjoin.ForkJoinPool pool = fjPool.getForkJoinPool();// tried fjPool.createPool as well
  </code></pre>
  
  <p>Notice the packeage is different. So I get a method signature error when I try to run. Any idea how to overcome this?</p>