Implement 3D slider state reading

src/Input.cpp

@@ -3,6 +3,8 @@
 
 namespace cpp3ds {
 
+	float Input::slider = 0;
+
 	int Input::getHID(){
 		last_hid = read_word(HID);
 		return last_hid;
@@ -12,4 +14,8 @@ namespace cpp3ds {
 		return (~read_word(HID) & button);
 	}
 
+	void Input::update3DSlider(){
+		Input::slider = (float)(read_word(SLIDERSTATE) & 0xFF) / 255;
+	}
+
 }