game_players.role can be one of 'black', 'white' or 'user'
- Add "black_cd", "black_rank_cd", "white_cd" and "white_rank_cd"
  to "game_players" table
- Add "user_cd" and "user_rank_cd" to "games" table
- Rename games.user to games.user_name
- Rename games.black to games.black_name
- Rename games.white to games.white_name
Remove the following columns from the games table:
  - file_format
  - charset
  - style
  - application
  - game_type