- issue #47: make log attribute optional
- issue #47: make log attribute optional

0u812/libSEDML,0u812/libSEDML,0u812/libSEDML,fbergmann/libSEDML,fbergmann/libSEDML,0u812/libSEDML,fbergmann/libSEDML,fbergmann/libSEDML