Initial release. The analytic one, two and three compartment linear
solutions, their 'stan' gradients, the eigen decompositions (solComp2(),
solComp3()) and the derived-parameter conversions behind
rxode2::rxDerived() moved here from 'rxode2', so 'rxode2' no longer
compiles 'stan'. 'rxode2' reaches the compiled kernels through an
external-pointer table and hands this package the struct offsets it needs,
so neither package shares struct layouts with the other.
The package neither links nor loads the TBB library: the 'stan' autodiff tapes are created per thread here, so 'RcppParallel' is needed only for its headers.
The closed-form solutions follow the idea of the 'wnl' package by Kyun-Seop Bae; the implementation here is different.