Add parameter to print null cells

[RenatoPasquini]

Hi, I would like to contribute to this code. I create a parameter (p_print_null_cells) in the read function to consider the null cells present in the xlsx.

[antonscheffer]

Hm, I've never heard of anyone who needed this. But anyway, after a quick review:

• it uses an unknown type t_str_array
• wouldn't this replacement for get_next_cell be simpler, also handles more than 26 columns

  
  function get_next_cell( p_cell varchar2) return varchar2 is
  begin
  return alfan_col( col_alfan( rtrim( p_cell, '0123456789' ) ) + 1 )
      || ltrim( p_cell, 'ABCDEFGHIJKLMNOPQRSTUVWXYZ' );
  end;