title: Generate AffineTransform from 3 points
body: <p>Given 3 points (x and y coordinates) in coordinate system A, and 3 corresponding points in coordinate system B, how can I derive an AffineTransform that will convert from A to B.</p>
  
  <p>My question is similar to <a href="https://stackoverflow.com/questions/14015456/create-transform-to-map-from-one-rectangle-to-another">Create transform to map from one rectangle to another?</a>, except that question only deals with 2 points - i.e., it assumes there is no rotation.</p>