Could also be helped by perfect branch prediction

The use of void* in the interface is not my favorite solution...

See https://github.com/usnistgov/teqp/issues/9

Should speed up compilation a smidge

To avoid circular dependency in what is to come

A polish was needed after perturbation (duh!)

See https://github.com/autodiff/autodiff/commit/5a8501f36b537a0663105b1288f29801dec495a6

Just need to fill in the remaining terms and test, test, test