- add "ranks" table
- rename go_players.black_rank to black_rank_cd
- rename go_players.white_rank to white_rank_cd
- rename rengo_players.black1_rank to black1_rank_cd
- rename rengo_players.black2_rank to black2_rank_cd
- rename rengo_players.white1_rank to white1_rank_cd
- rename rengo_players.white2_rank to white2_rank_cd
add games.game_type
- add "game_dates" table
- remove games.date