- and added database struct can execute some postgres sekai database action
- now can insert a Song (without its Difficulties)
- now can search if a Song exists(by id)
- added a SekaiDifficulties type struct targeting to database type
- added a struct SekaiSongDifficulties.DatabaseStruct targeting to database its table struct
- added a class PostgresSession for manager a database action flow
- and reforged PostgresConfig#connect() to implement it
- added charset param in database import command
- moved PostgresConfig to sekai-db proj
- added dependency gson
- added data_tool/sekai_master_db with a Music which can parse sekai-master-db musics.json and convert it to the Song object
- change the id and seq and name def of SongUnit
- change and added fields to Song
- change and added fields to Difficulty
- add subproj sekai-database for db connection and action(empty currently)
- add sekai-cli command database to execute database manager action(no implementation currently)