def change_column_width(column_index, width_in_chars = RubyXL::ColumnRange::DEFAULT_WIDTH)
      change_column_width_raw(column_index, ((width_in_chars + (5.0 / RubyXL::Font::MAX_DIGIT_WIDTH)) * 256).to_i / 256.0)
    end
def change_column_width(column_index, width_in_chars = RubyXL::ColumnRange::DEFAULT_WIDTH)
      change_column_width_raw(column_index, ((width_in_chars + (5.0 / RubyXL::Font::MAX_DIGIT_WIDTH)) * 256).to_i / 256.0)
    end
Get column width measured in number of digits, as per
 http://msdn.microsoft.com/en-us/library/documentformat.openxml.spreadsheet.column%28v=office.14%29.aspx