Time for action – adjacent squares

1. Add the findAdjacentNodes() method to the Helper Methods region of the PathFinder class:

   static private List<PathNode> findAdjacentNodes(
       PathNode currentNode, 
       PathNode endNode)
   {
       List<PathNode> adjacentNodes = new List<PathNode>();
   
       int X = currentNode.GridX;
       int Y = currentNode.GridY;
   
       bool upLeft = true;
       bool upRight = true;
       bool downLeft = true;
       bool downRight = true;
   
       if ((X > 0) && (!TileMap.IsWallTile(X - 1, Y)))
       {
           adjacentNodes.Add(new PathNode(
                   currentNode,
                   endNode,
                   new Vector2(X - 1, Y),
                   CostStraight + currentNode.DirectCost));
       }
       else
       {
           upLeft = false;
           downLeft = false;
       }
   
       if ((X < 49) && (!TileMap.IsWallTile(X + 1, Y)))
       {
           adjacentNodes.Add(new PathNode(
                   currentNode,
                   endNode,
                   new Vector2(X + 1, Y...