code: @Pure
  	public AroundCellIterable<P> getGridCellsAround(Point2D<?, ?> position, double maximalDistance) {
  		final int column = getColumnFor(position.getX());
  		final int row = getRowFor(position.getY());
  		return new AroundIterable(row, column, position, maximalDistance);
  	}
docs: Replies the cells around the specified point.
  The order of the replied cells follows cocentric circles
  around the cell that contains the specified point.
  
  @param position the position.
  @param maximalDistance is the distance above which the cells are not replied.
  @return the iterator on the cells.