for consistency with other interface classes

    t = re.sub(r'(\W)(Simulation)(\W)', r'\1I\2\3', t)
    t = re.sub(r'(/)I(Simulation)', r'\1\2', t)

rm unused functions; move Bessel fcts to separate source pair

new function SimulationResult::max(), and some minor edits

Various simplifications in GISASSimulation indirecting towards scattering computation; update include guards

This is incorrect, but everything else would be worse.
Especially, there was no justification for the previous hack.