nlmixr2est 3.0.1

New features

Now when optimizing only a single parameter with focei-family,
will change to use stats::optimize() for the outer problem (#481)
When estimating with all fixed population parameters, do a posthoc
estimation.
Internally removed assignInMyNamespace() replacing with
nlmixr2global, which fixes some edge case bugs where the nlmixr2
environment was not reset properly.
Treated edge case where all initial parameters are zero and change
scaling from scaled to unscaled (#486)
Added mu4 referencing that will change string expressions to
rxode2 numeric values. This allows derived strings to also be
treated as mu expressions (#484)