Support for FBA FROG analysis

SBSCL has a working FBA model solver. As part of the recent HARMONY we developed basic FROG guidelines. See also https://github.com/matthiaskoenig/fbc_curation/. SBSCL should support the generation of these files for a given FBA model. This would allow to check reproducibility easily between different solvers. The biomodels database team would apply these guidelines for FBA model curation.