private void ApplyGroupingToAdjacents(OccupiedGridSquare square, IEnumerable <OccupiedGridSquare> usedSquares)
{
var adjacents = usedSquares.Where(other => other.Group == 0 && square.IsAdjacentTo(other))
.ToList();
adjacents.ForEach(sq => sq.Group = square.Group);
adjacents.ForEach(sq => ApplyGroupingToAdjacents(sq, usedSquares));
}
