GitLab

* Support GROMOS bond and angle types

* Support NBFIX with geometric combining rule

* Continuing GROMOS support

* Bug fixes

* Fixes to test case

* Update wrappers/python/openmm/app/gromacstopfile.py
Co-authored-by: Jason Swails <jason@entos.ai>

* Improve logic for handling dihedraltypes

---------
Co-authored-by: Jason Swails <jason@entos.ai>