GBRV update and JTH testing

These notes contain a discussion of a minor update of the GBRV potentials as well as new testing data on both the GBRV potentials and the recently released JTH PAW set. This testing includes a new zinc blende test set, which has been examined with the ∆-factor test[1]. The updated testing data are consistent with earlier tests which show very good performance for the GBRV potential set. The tests on the JTH set indicate that while the majority of the PAWs are sufficiently accurate, the JTH PAW table requires revisions before it is sufficiently robust for general use in high-throughput computations.