Time for action – power-ups

1. Add the following declarations to the WeaponManager class:

   static public List<Sprite> PowerUps = new List<Sprite>();
   static private int maxActivePowerups = 5;
   static private float timeSinceLastPowerup = 0.0f;
   static private float timeBetweenPowerups = 2.0f;
   static private Random rand = new Random();

2. Add the tryToSpawnPowerup() method to the Weapons Management Methods region of the WeaponManager class:

   private static void tryToSpawnPowerup(int x, int y, WeaponType type)
   {
       if (PowerUps.Count >= maxActivePowerups)
       {
           return;
       }
   
       Rectangle thisDestination = 
           TileMap.SquareWorldRectangle(new Vector2(x,y));
   
       foreach (Sprite powerup in PowerUps)
       {
           if (powerup.WorldRectangle == thisDestination)
           {
               return;
           }
       }
   
       if (!TileMap.IsWallTile(x,y))
       {   
           Sprite newPowerup = new Sprite(
               new Vector2(thisDestination.X, thisDestination.Y),
               Texture,
        ...