Fix player save data issue & multiple username implementations (#257)

* fix saving issue & multiple username implementations

* Update README.md

Updated the method for overriding in-game username from '-name' to 'username.txt'.

* remove unused include i forgot to get rid of while testing

Minecraft.Client/Windows64/4JLibs/inc/4J_Profile.h

@@ -75,7 +75,7 @@ public:
 	// SYS
 	int					GetPrimaryPad();
 	void				SetPrimaryPad(int iPad);
-	char*				GetGamertag(int iPad);
+	const char*			GetGamertag(int iPad);
 	wstring				GetDisplayName(int iPad);
 	bool				IsFullVersion();
 	void				SetSignInChangeCallback(void ( *Func)(LPVOID, bool, unsigned int),LPVOID lpParam);