Support execution of SBML comp models about amici

[dweindl]

This requires fixing some additional issues in #2063, #2064. Won't be able to do that during the next week, but will try to look into that thereafter.

[matthiaskoenig]

This is perfect. Just tested and works. Can be closed from my side. Thanks a lot.

[matthiaskoenig]

Basically you just have to do the following on the SBMLDocument:

    props = libsbml.ConversionProperties()
    props.addOption("flatten comp", True)  # Invokes CompFlatteningConverter
    props.addOption("leave_ports", False)  # Indicates whether to leave ports
    props.addOption("abortIfUnflattenable", "none")

    # flatten
    result = doc.convert(props)
    flattened_status = result == libsbml.LIBSBML_OPERATION_SUCCESS

[dweindl]

Thanks, will add it.

[dweindl]

That should work now on branch develop. For fbc, only extra attributes to core elements are supported, but no additional fbc elements.