title: Write numpy structured array using savetxt
body: <p>I faced a problem with writing structured array in txt file.
  Having an output file (<em>outfile</em>) opened, I use the following numpy function:</p>
  
  <pre><code>np.savetxt(*outfile*, ***recarray***, fmt=['%s','%-7.4f','%-7.4f','%-7.4f'])
  </code></pre>
  
  <p>The <strong><em>recarray</em></strong> is like [ (b'H', 0.9425, 0.1412, 7.1414) ... (b'N', 1.0037, 4.0524, 6.8000) ], where the first element has <code>numpy.bytes_</code> type and others are <code>numpy.float64</code>. </p>
  
  <p>An error message appears while writing this recarray in file:</p>
  
  <pre><code>TypeError: must be str, not bytes
  </code></pre>
  
  <p>So, what is the easiest way to put this array in file? Maybe there is another function?</p>