Time for action – updating GameBoard to support animatedpieces

1. In the declarations section of the GameBoard class, add three dictionaries:

   public Dictionary<string, FallingPiece> fallingPieces = 
       new Dictionary<string, FallingPiece>();
   public Dictionary<string, RotatingPiece> rotatingPieces = 
       new Dictionary<string, RotatingPiece>();
   public Dictionary<string, FadingPiece> fadingPieces = 
       new Dictionary<string, FadingPiece>();

2. Add methods to the GameBoard class to create new falling piece entries in the dictionaries:

   public void AddFallingPiece(int X, int Y, 
       string PieceName, int VerticalOffset)
   {
       fallingPieces[X.ToString() + "_" + Y.ToString()] = new
           FallingPiece(PieceName, VerticalOffset);
   }
   
   public void AddRotatingPiece(int X, int Y, 
       string PieceName, bool Clockwise)
   {
       rotatingPieces[X.ToString() + "_" + Y.ToString()] = new 
           RotatingPiece(PieceName, Clockwise);
   }
   
   public void AddFadingPiece(int X, int Y, string...