[Enhance][Bug fix] Improve setting file & ...

- Fix a small bug that `best30` of API cannot have scores whose songs are not in database
- At present the setting file can be a module or a file with some of options
- Limiter can have multiple rules together now

latest version/core/user.py

@@ -3,9 +3,8 @@ import hashlib
 import time
 from os import urandom
 
-from setting import Config
-
 from .character import UserCharacter, UserCharacterList
+from .config_manager import Config
 from .constant import Constant
 from .error import (ArcError, DataExist, FriendError, InputError, NoAccess,
                     NoData, UserBan)