Regularize PSF inputs #154
Description
In the ideal world, a code can call PSF.get_psf_object, pass the psfclass that the user gave it on the command line, and not have to know anything else.
In practice, different PSF subclasses take different arguments. (E.g., if you want to use a varying gaussian PSF, you have to pass the right things to make it go. If you want ou2024 PSFs, you give it different stuff from basic image clip PSFs. Etc. They're all different.)
It would be good to get back to the ideal world, if that's possible.
One way to do it would be painful for everybody calling the PSFs, and that would be to just allow the user to specify additional parameters on the command line to customize which PSF is being used. Perhaps some library support for that kind of thing would be useful?
Think about the right way to do this.
(The goal is to avoid any if blocks, or anything in code that uses snappl as a library that knows which PSF class is being used, because that means we've missed the point of a lot of the PSF abastraction we're trying to do.)