Add AUCtau to the NCA output, if multi-dose PK data
nca_add_auctau.RdWill copy auclast to auctau in the NCA output, for
those intervals where the end of the interval is <Inf.
nca_add_auctau.RdWill copy auclast to auctau in the NCA output, for
those intervals where the end of the interval is <Inf.