------------------
* Fixed module naming in docs using __module__.
* Converted DirectedGraph nodes to a list.
* Added Code of Conduct.
* Added GraphTransliterator class.
* Updated module dependencies.
* Added requirements.txt
* Added check_settings parameter to skip validating settings.
* Added tests for ambiguity and `check_ambiguity` parameter.
* Changed name to Graph Transliterator in docs.
* Created core.py, validate.py, process.py, rules.py, initialize.py,
exceptions.py, graphs.py
* Added ignore_errors property and setter for transliteration
exceptions (UnrecognizableInputToken, NoMatchingTransliterationRule)
* Added logging to graphtransliterator
* Added positive cost function based on number of matched tokens in rule
* added metadata field
* added documentation