memory efficiently reorder NumericalDerivator members
memory efficiently reorder NumericalDerivator members

Co-authored-by: Stephan Hageboeck <4db7e0e579e9b6a6dd6449b1d334cf5749aaf6de@cern.ch>
olifre/root,olifre/root,olifre/root,olifre/root,olifre/root,olifre/root,olifre/root,olifre/root,olifre/root,olifre/root,olifre/root