Vaggelis Papoutsis authored Dec 09, 2021 and Andrew Heather committed Jun 10, 2022

Each solver now writes its sensitivity derivatives to its dictionary,
enabling also a binary format. If present, the sensitivities are then
re-read from the dictionary, avoiding thus possible loss of information
due to re-computation.

As a side-effect, sensitivities are computed after the completion of
each adjoint solver, instead of being computed after all adjoint solvers
have been completed.