Get all of the parameters from a flexmodel in a vector that is ready to be passed to a TMB AD objective function, gradient function, hessian function, simulate function, report function.
tmb_params(model)flexmodel
Currently this includes params and if spec_ver_gt('0.1.0')
it also includes time-varying multipliers in
model$timevar$piece_wise$schedule$last_tv_mult. If
spec_ver_gt('0.1.2'), only the parameters to be optimized are
returned.