HLookup need an ordered list even if range_lookup is set to false

[jtattevin]

This is:

- [x] a bug report
- [ ] a feature request
- [ ] **not** a usage question (ask them on https://stackoverflow.com/questions/tagged/phpspreadsheet or https://gitter.im/PHPOffice/PhpSpreadsheet)

What is the expected behavior?

If range_lookup is FALSE (require exact match), values in the first row of table do not need to be sorted.

What is the current behavior?

HLOOKUP assume that the list is always sorted, so if the searched value is after a value bigger, the hlookup will return a #N/A

What are the steps to reproduce?

<?php

use PhpOffice\PhpSpreadsheet\IOFactory;
use PhpOffice\PhpSpreadsheet\Spreadsheet;

require 'vendor/autoload.php';

$spreadsheet=new Spreadsheet;
$workSheet = $spreadsheet->getActiveSheet();


$workSheet->setCellValue('A1', 'SMALL');
$workSheet->setCellValue('B1','MEDIUM');
$workSheet->setCellValue('C1', 'LARGE');

$workSheet->setCellValue('A2', '1');
$workSheet->setCellValue('B2','2');
$workSheet->setCellValue('C2', '3');


$workSheet->setCellValue('D1', 'LARGE');
$workSheet->setCellValue('D2', '=HLOOKUP(D1, A1:C2, 1, 0)');

echo $spreadsheet->getActiveSheet()->getCell('D2')->getCalculatedValue().PHP_EOL;
$writer = IOFactory::createWriter($spreadsheet, 'Xls');
$writer->save('test.xls');

Which versions of PhpSpreadsheet and PHP are affected?

Tested with version 1.6, 1.8.1 and dev-master d4eab49

The lines causing this are https://github.com/PHPOffice/PhpSpreadsheet/blob/master/src/PhpSpreadsheet/Calculation/LookupRef.php#L797