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Removed invalid code in getLanguageFileDescription,When the language is not discovered, it will use the built-in language fallback mechanism to fall back,At the same time, we also fix the issue that using language in the server does not save the settings of the server side locale

* Fix the following issues:
1. HashMap non-thread-safe issus
2. Fix the same problem in pr621, but use a better implementation

Add the following functions:
1. There is now a language cache inside getLanguage to prepare for different languages corresponding to different time zones where the accounts in the server are located

* add /language command,each account has their own Locate

fix issue 648 677

fix #629