Internalized the _nameFromCoords and _coordsFromName methods. Simplified king castling in board, as well as removed sideaffects from 'square' method
Fix a typo in comments.
fixed 4 failing unit tests.
renamed tests folder simply to test
Changed color to be an enum.
Separated out current player from chess board string. Simplified pieces by removing has_moved property from pieces that do not use it.