Drop members for which there are methods; rename _()s.
Drop bs3ddist; add betagamma(), *ctau().
Put bs3ddist back until we validate.
use_track() and ngoodtracks()
Fix bug in MFVVertexAuxSorter::by_mass.
VertexAux members -> methods.
Fix bug in _rms.
maxmntrackpt returns -1 when n not valid.