Read FAC atomic data

As you say adf04 isn't a special file type so I propose adding an option to use FAC atomic data in ColRadPy FAC promises it can do everything. In particular, I'm paying attention to knowing how to make: - Spontaneous emission rates - 2-photon emission rates - Collision excitation/de-excitation rate coefficients - Radiative recombination rate coefficients - Dielectronic recombination strengths (+autoionization rates) - Collisional ionization (+innershell) rate coefficients The FAC documentation seems suggest it can't do three-body recombination. Currently, I've been using a FAC-function that automatically convolutes cross-sections with a Maxwellian but can do an option for something more general. I know how to read the FAC data files so I propose to do this. Is there any hiccups you'd foresee? For the rate coefficients, I'd be giving it a function of Te in units [cm3/s]. Looking at the structure of `colradpy.data['rates']` I'm not actually sure how to incorporate the autoionization rates. I'd guess I can just sum the spontaneous emission and 2-photon emission rates hopefully being aware of the different broadening. FAC also gives cross-section data so I propose also including an electron energy distribution function (EEDF) convolution function in the event you didn't use FAC's tools to convolute a Maxwellian vs. Te. I'd guess it'd be reasonable to assume anyone interested in using this functionality know how to set the cross-section energy grid in FAC themselves so it can be assumed the given cross-section data is sufficient for the desired EEDF. Thoughts on this?