title: Not enough points(2) supplied to Voronoi
body: <p>I'm trying to compute a Voronoi Diagram for only two points:</p>
  
  <pre><code>from scipy.spatial import Voronoi
  vor = Voronoi([[0, 0], [0, 1]])
  </code></pre>
  
  <p>but get the following error:</p>
  
  <pre><code>    vor = Voronoi(points)
    File "qhull.pyx", line 2518, in scipy.spatial.qhull.Voronoi.__init__
    File "qhull.pyx", line 354, in scipy.spatial.qhull._Qhull.__init__
  scipy.spatial.qhull.QhullError: QH6214 qhull input error: not enough points(2) to construct initial simplex (need 4)
  
  While executing:  | qhull v Qc Qz Qbb
  Options selected for Qhull 2015.2.r 2016/01/18:
    run-id 12883022  voronoi  Qcoplanar-keep  Qz-infinity-point  Qbbound-last
    _pre-merge  _zero-centrum  Qinterior-keep
  </code></pre>
  
  <p>Is this expected behaviour? I'm splitting MultiPolygons based on a set of points contained within them, and in one of the cases there are only two points. </p>