title: Find unique rows in numpy.array
body: <p>I need to find unique rows in a <code>numpy.array</code>.</p>
  
  <p>For example:</p>
  
  <pre><code>&gt;&gt;&gt; a # I have
  array([[1, 1, 1, 0, 0, 0],
         [0, 1, 1, 1, 0, 0],
         [0, 1, 1, 1, 0, 0],
         [1, 1, 1, 0, 0, 0],
         [1, 1, 1, 1, 1, 0]])
  &gt;&gt;&gt; new_a # I want to get to
  array([[1, 1, 1, 0, 0, 0],
         [0, 1, 1, 1, 0, 0],
         [1, 1, 1, 1, 1, 0]])
  </code></pre>
  
  <p>I know that i can create a set and loop over the array, but I am looking for an efficient pure <code>numpy</code> solution. I believe that there is a way to set data type to void and then I could just use <code>numpy.unique</code>, but I couldn't figure out how to make it work.</p>