Revert some changes to 'ModelSpectrum' object
Revert some changes to 'ModelSpectrum' object

tacaswell/scikit-beam,Nikea/scikit-xray,tacaswell/scikit-beam,tacaswell/scikit-xray,tacaswell/scikit-xray,tacaswell/scikit-beam,scikit-xray/scikit-xray,Nikea/scikit-xray,tacaswell/scikit-xray,scikit-xray/scikit-xray,scikit-xray/scikit-xray,Nikea/scikit-xray