get_model_names() does not return MagmaSat in list

[kaylai]

There is maybe an internal reason for returning all models except MagmaSat for this function call, since MagmaSat is treated differently and separately from all other models. But, for the user, it is confusing that we don't return MagmaSat in the list of model names. Should be easy to track down and fix.

Note also that there are two functions: get_model_names() and get_models() that I think are unnecessary duplicates, so those should be cleaned up as well.