This work has been supported since the initial version in part by the National Science Foundation,
Grant Numbers PHY 96-00049, 00-96522, 03-53180, 06-52448, 09-65133, 12-60995 and 13-06069, and by the
National Aeronautics and Space Administration, Grant Numbers NAG5-10186 and NNG-06GI60G. We also
gratefully acknowledge the continuing hospitality of the Institut d’Astrophysique de Paris, where portions of
this update were completed. We thank Luc Blanchet for helpful comments, and Michael Kramer and
Norbert Wex for providing useful figures. We are particularly grateful to Norbert Wex and Nicolás Yunes
for detailed and comprehensive comments.