PhotoCalib::computeScalingTo currently raises "not implemented", because I didn't have an clear approach given the available methods in BoundedField. I suspect a proper implementation would require operator*(BoundedField), which may only make sense for same-type BoundedFields (e.g. Chebyshev to Chebyshev).

This ticket is to finish the implementation of that method, with whatever additions to BoundedField are necessary.