Contributed by Nicholas Firth.

For more information on the Plane of Best Fit please see
http://pubs.acs.org/doi/abs/10.1021/ci300293f

 If this code has been useful to you, please include the reference
 in any work which has made use of it:
 Plane of Best Fit: A Novel Method to Characterize the
 Three-Dimensionality of Molecules,
 Nicholas C. Firth, Nathan Brown, and Julian Blagg, Journal of
 Chemical Information and Modeling 2012 52 (10), 2516-252

- PBFRDKit.cpp includes an implementation of the PBF method.
- demo.cpp includes an example of using the method and also tests,
  using data from the testData directory, that results are correct.
- testData/egfr.sdf is sample data taken from DUD
- testData/egfr.out is reference output data

Usage requires a local installation of Eigen (http://eigen.tuxfamily.org/),
which is used internally to solve the eigenvalue problem.