Rework the GUI so it uses SFMLBackend by moving the SoundQuip into SFMLBackend.

sfmlbackend.hpp

@@ -3,6 +3,8 @@
 #include <SFML/Graphics/RenderWindow.hpp>
 #include <SFML/Graphics/Sprite.hpp>
 #include <SFML/Graphics/Font.hpp>
+#include <SFML/Audio.hpp>
+#include <nlohmann/json.hpp>
 #include "game_engine.hpp"
 #include <string>
 
@@ -15,6 +17,19 @@ constexpr int TEXT_SIZE = 48;
 constexpr int Y_LINES = 23;
 constexpr int X_ROWS = 48;
 
+class SoundQuip {
+public:
+  sf::Sound sound;
+  sf::SoundBuffer buffer;
+  bool initialized;
+
+  SoundQuip() {};
+
+  void load(nlohmann::json &data, const char *in_file);
+  void play();
+  void stop();
+};
+
 class SFMLBackend {
   sf::ContextSettings settings;
   sf::RenderWindow window;