title: Time difference in seconds from numpy.timedelta64
body: <p>How to get time difference in seconds from numpy.timedelta64 variable?</p>
  
  <pre><code>time1 = '2012-10-05 04:45:18'
  time2 = '2012-10-05 04:44:13'
  dt = np.datetime64(time1) - np.datetime64(time2)
  print dt
  
  0:01:05
  </code></pre>
  
  <p>I'd like to convert <code>dt</code> to number (int or float) representing time difference in seconds.</p>