- use namespace bracket all content in documentation to reduce useless namespace prefix.
- change the argument type of AbstractSetting and CoreManager to yycc_u8string_view instead of const yycc_char8_t*.
- throw exception if given setting name is invalid in ConfigManager, instead of slient fallback.
- add documentation for win fct helper
- add new macro YYCC_U8_CHAR for casting ordinary char to yycc utf8 char.
- add documentation for new added YYCC_U8_CHAR.
