add possibility to provide combined atomic and magnetic form factors for AtomMixed type structure

[tox1c90]

It should be possible to provide combined atomic and magnetic form factors for an AtomMixed type structure object. This becomes particularly important in case of using experimentally obtained form factors that were not measured individually for each type of atom but for a whole layer or alloy consisting of more than one element.

[dschick]

thanks for pointing that out!

I guess it is straight forward to implement that. So in case an atomic_form_factor_path or magnetic_form_factor_path is given for the AtomMixed these values will be used. The fallback will be the averaging of the individualt form factors of the Atoms as it is done now.

[dschick]

Hi @tox1c90 , could you please check #77 if it solves the issue?

[dschick]

solved by #77