Implemented load audio and music files as well the basic audio playback

functionality.

include/GameEngine.h

@@ -6,19 +6,50 @@
 #include "SDL_pixels.h"
 #include "reusable_ids.h"
 #include <stdbool.h>
+#include <stdint.h>
 
 #ifdef __cplusplus
 extern "C" {
 #endif // !__cplusplus
 
-bool init_game(const char *game_name, int window_width, int window_height,
-               SDL_Color window_background_color, bool full_screen);
+bool init_game(const char *game_name, uint32_t window_width,
+               uint32_t window_height, SDL_Color window_background_color,
+               bool full_screen, uint8_t audio_tracks);
 bool game_running();
 ObjectID add_object(void *object, EventHandlerPtr eh, UpdateFuncPtr uf,
                     RenderFuncPtr rf);
 void remove_object(ObjectID *id);
 AssetID load_asset(const char *path, AssetType type);
 void render_texture_asset(AssetID id, float x, float y, float w, float h);
+int8_t play_audio_asset(AssetID id, int16_t loops, bool fade_in,
+                        uint32_t fade_length_in_ms);
+void pause_audio_asset_on_track(AssetID id, uint8_t track);
+void resume_audio_asset_on_track(AssetID id, uint8_t track);
+void stop_audio_asset_on_track(AssetID id, uint8_t track);
+void fade_out_audio_asset_on_track(AssetID id, uint8_t track,
+                                   uint32_t fade_length_in_ms);
+void pause_all_instances_of_audio_asset(AssetID id);
+void resume_all_instances_of_audio_asset(AssetID id);
+void stop_all_instances_of_audio_asset(AssetID id);
+void fade_out_all_instances_of_audio_asset(AssetID id,
+                                           uint32_t fade_length_in_ms);
+int8_t get_audio_asset_volume(AssetID id);
+void set_audio_asset_volume(AssetID id, int8_t volume);
+void play_music_asset(AssetID id, int16_t loops, bool fade_in,
+                      uint32_t fade_length_in_ms);
+void pause_music_asset(AssetID id);
+void resume_music_asset(AssetID id);
+void stop_music_asset(AssetID id);
+void fade_out_music_asset(AssetID id, uint32_t fade_length_in_ms);
+int8_t get_music_asset_volume(AssetID id);
+void set_music_asset_volume(AssetID id, int8_t volume);
+bool is_music_asset_playing(AssetID id);
+void pause_playing_music();
+void resume_playing_music();
+void stop_playing_music();
+void fade_out_playing_music(uint32_t fade_length_in_ms);
+void set_playing_music_volume(int8_t volume);
+bool is_music_playing();
 void close_asset(AssetID *id);
 void handle_events();
 void update();