Added option for turn on/off smooth scroll

src/states/OptionsState.h

@@ -16,7 +16,8 @@ private:
         Fullscreen = 0,
         Music = 1,
         SoundFx = 2,
-        Back = 3
+        SmoothScroll = 3,
+        Back = 4
     };
 
     static constexpr int MAX_NAME_LENGTH = 12;
@@ -29,8 +30,10 @@ private:
     void toggleFullscreen();
     void toggleMusic();
     void toggleSoundFx();
+    void toggleSmoothScroll();
     void exitToMenu();
     bool isFullscreen() const;
     bool isMusicEnabled() const;
     bool isSoundFxEnabled() const;
+    bool isSmoothScrollEnabled() const;
 };