Moved away from singleton pattern

Signed-off-by: Hans Kokx <hans.d.kokx@gmail.com>

packages/wolf_3d_flutter/lib/audio/audio_adaptor.dart

@@ -3,48 +3,52 @@ import 'package:wolf_3d_dart/wolf_3d_engine.dart';
 import 'package:wolf_3d_flutter/wolf_3d.dart';
 
 class FlutterAudioAdapter implements EngineAudio {
+  final Wolf3d wolf3d;
+
+  FlutterAudioAdapter(this.wolf3d);
+
   @override
   void playLevelMusic(WolfLevel level) {
-    Wolf3d.I.audio.playLevelMusic(level);
+    wolf3d.audio.playLevelMusic(level);
   }
 
   @override
   void stopMusic() {
-    Wolf3d.I.audio.stopMusic();
+    wolf3d.audio.stopMusic();
   }
 
   @override
   void playSoundEffect(int sfxId) {
-    Wolf3d.I.audio.playSoundEffect(sfxId);
+    wolf3d.audio.playSoundEffect(sfxId);
   }
 
   @override
   void playMenuMusic() {
-    Wolf3d.I.audio.playMenuMusic();
+    wolf3d.audio.playMenuMusic();
   }
 
   @override
   Future<void> init() async {
-    await Wolf3d.I.audio.init();
+    await wolf3d.audio.init();
   }
 
   @override
   void dispose() {
-    Wolf3d.I.audio.dispose();
+    wolf3d.audio.dispose();
   }
 
   @override
   Future<void> debugSoundTest() async {
-    Wolf3d.I.audio.debugSoundTest();
+    wolf3d.audio.debugSoundTest();
   }
 
   @override
-  WolfensteinData? get activeGame => Wolf3d.I.activeGame;
+  WolfensteinData? get activeGame => wolf3d.activeGame;
 
   @override
   set activeGame(WolfensteinData? value) {
     if (value != null) {
-      Wolf3d.I.setActiveGame(value);
+      wolf3d.setActiveGame(value);
     }
   }
 }