sbgn-ml support

Current implementation skip some glyphs/arc that can be used when importing model from SBGN. We should improve ETL to support those types. Here is the list: https://docs.google.com/document/d/1UG7EGNAV1UKGmpCTZC9SBDGt7rbIJDWeu4KRWZ0hqKY/edit?usp=sharing