Adding SoundManager to the game engine

Open the Engine.h file and add an instance of the new SoundManager class, as shown in the following highlighted code:

#pragma once
#include <SFML/Graphics.hpp>
#include "TextureHolder.h"
#include "Thomas.h"
#include "Bob.h"
#include "LevelManager.h"
#include "SoundManager.h"
using namespace sf;
class Engine
{
private:
    // The texture holder
    TextureHolder th;
    // Thomas and his friend, Bob
    Thomas m_Thomas;
    Bob m_Bob;
    // A class to manage all the levels
    LevelManager m_LM;
    // Create a SoundManager
    SoundManager m_SM;
    const int TILE_SIZE = 50;
    const int VERTS_IN_QUAD = 4;

At this point, we could use m_SM to call the various play....