def push(cell)
      cell = Workbook::Cell.new(cell, {row:self}) unless cell.class == Workbook::Cell
      super(cell)
    end
def push(cell)
      cell = Workbook::Cell.new(cell, {row:self}) unless cell.class == Workbook::Cell
      super(cell)
    end
Add cell
 @param [Workbook::Cell, Numeric,String,Time,Date,TrueClass,FalseClass,NilClass] cell or value to add