[cctbxbb] Adding more parameters to xray::scatterer for anharmonic thermal displacements

Hi, we are working with Michal Chodkiewicz (Warsaw University) to add anharmonic thermal tensors to smtbx refinement. I was thinking to add one pointer to xray::scatterer, which can be NULL. When it is not so, it would point to an object which can compute the value and the derivatives for that thermal factor. That means we would have a base class with virtual methods, but I would say that is our problem! The issue for the rest of the cctbx community is the extra storage of that pointer in that class. Would that be all right? I remember quite a few years ago Ralf saying he wanted to replace the ADP's by a pointer to an external storage to save space. Our idea is along the same line. Best wishes, Luc