feat: username.txt support

4J_Profile/Windows64/PRO_Sys.h

@@ -11,6 +11,7 @@ public:
 	bool IsGuest(int iQuadrant);
 
 	// GAMERTAG
+	void LoadGamertag();
 	void SetFakeGamertag(char *name);
 	char* GetGamertag(int iPad);
 	wstring GetDisplayName(int iPad);