Loading model objects between different versions of TMB

[kaskr]

Description:

It would be nice if saved model objects would remain valid when updating to new versions of TMB - see e.g. https://github.com/glmmTMB/glmmTMB/issues/651 .

Solution idea:

Currently, a TMB model object contains functions (e.g. fn and gr) that explicitly .Call underlying cpp code. This design is highly sensitive to changes in the cpp API. The TMB R code might benefit from re-factoring all the .Call into separate R functions with a fixed R API.