====================
- Added a new exception class ``MalformedPolygonError`` which replaces
``ValueError`` which replaced ``AssertionError`` in the
``Graph._sanity_check()`` method. Also replaced ``ValueError`` with
``RuntimeError`` in ``Graph.Edge.follow()`` method. Added error
messages to some other exceptions. [207]
- Updated CI/CD to use github actions, instead of Travis CI.
- To comply with ``bandit`` all ``assert`` statements were changed to standard
``if`` checks and raising the appropriate errors.