Using right preconditioning provides a more reliable performance benefit
even after the ignition event, allowing the solver to take reasonable
timesteps and showing a CPU-time benefit even for a single reactor with
the 100-species n-dodecane mechanism.

Finite differences were being calculated incorrectly due to the arguments
to the eval function being misinterpreted.

This is a useful reference for checking analytic or approximate Jacobian
formulations, even if it isn't a particularly good Jacobian to use for
integration generally.

Make exclusion of terms that cause Jacobian to be dense explicit
rather than accidental.

Include full derivatives of species equation in the derivatives of the
energy equation, since this does not affect sparsity.