title: Double-ended queue in h5py
body: <p>In my project I use python's deque as a limited buffer. The problem is a lack of RAM. That's why I'm looking for a solution and one option is to store the buffer on HDD. </p>
  
  <p>I'm wondering if it is possible to enable limited deque in h5py's datasets.</p>
  
  <p>Any advice is welcome.</p>