bring audio functions into cat_api.h

main.c

@@ -133,6 +133,7 @@ int main(int argc, char** argv)
 {
 	cat_init();
 	cat_create_window(1920, 1080);
+	cat_play_wav("etc/example.wav");
 	cat_fill(0, 1, 0, 0, screen_width - 1, screen_height - 1, 132, 155, 132);
 	while (1) game_loop();
 	return 0;