ENH: First beginnings of a categorical array type
ENH: Start of i/o module
REF: Get fill-map-vector working properly
ENH/REF: Add string parsers for CSV import
Update README.md
ENH: Update Arrays, add subsetting and index filtering
TST/DOC: Add tests and docstrings for subset function
REF: Change up data structure to hashmap for levels
REF: Rewrite array creation to be a single-pass function
REF/TST: Add type hinting, add more tests for arrays
TST: Add test coverage for arrays.clj