title: Cannot use 128bit float in Python on 64bit architecture
body: <p>I checked the size of a pointer in my python terminal (in Enthought Canopy IDE)
  via </p>
  
  <pre><code>import ctypes
  print (ctypes.sizeof(ctypes.c_voidp) * 8)
  </code></pre>
  
  <p>I've a 64bit architecture and working with <code>numpy.float64</code> is just fine. But I cannot use <code>np.float128</code>?</p>
  
  <pre><code>np.array([1,1,1],dtype=np.float128)
  </code></pre>
  
  <p>or </p>
  
  <pre><code>np.float128(1)
  </code></pre>
  
  <p>results in:</p>
  
  <pre><code>AttributeError: 'module' object has no attribute 'float128'
  </code></pre>
  
  <p>I'm running the following version:</p>
  
  <pre><code>sys.version_info(major=2, minor=7, micro=6, releaselevel='final', serial=0)
  </code></pre>