Simplify FitSuiteParameters::numbersDiffer; correct error in FitSuiteParameters::numberOfFreeFitParameters (introduced by some earlier refactoring)

FormFactorCrystal is an IFormFactor, not an IFormFactorBorn, since it evaluates for WavevectorInfo, not for q.

Magnetic materials needs only to know about Transform3D, not about Rotation. This resolves another circular directory dependence.

rm spurious inheritance from ISimulation from reflectivity calculation classes, and mv them back to Multilayer/