Backport of 7.1-3.0 for BTA 1.7.7.0_02

What's Changed

• Security: now, the password entered by the user is not displayed in the server logs.
• Removed: command /version to avoid conflicts with other mods.
• Added: command /simplifiedauth (alias /as), performs the same function as the above command.
• Changed: player see only "Use /register...", when they aren't registered. The registered user does not see the message that he needs to register, only the login.