title: Doing math with PCL PointXYZ structs?
body: <p>What is the usual way to do math, addition, subtraction, on PCL (Point Cloud Library) data types, i.e. PointXYZ?  There don't seem to be operators defined even for the basics.</p>
  
  <p>I thought maybe the PCL way was to convert to Eigen vectors, but there doesn't seem to be a constructor for that either.</p>