title: Quaternion from two vector pairs
body: <p>I have two vector pairs (before and after rotation).</p>
  
  <p>before rotation:
  [x1,y1,z1]
  [x2,y2,z2]</p>
  
  <p>after rotation:
  [x1',y1',z1']
  [x2',y2',z2']</p>
  
  <p>How to create a quaternion representing this rotation?</p>