Reorganize Samples

The samples have become unwieldy when running them from a browser. In particular, the drop-down lists are fixed size with no scrolling, and many of them are now just too large. I have moved all the Calculation samples up a level, and broken several categories (Basic, Chart, DateTime, Engineering, Financial, and Reader) into several pieces.

Convert-Online (now found in the Engineering category) had a number of different problems which are now resolved. It is the only member with any significant code change.

samples/Engineering/ERF.php

@@ -0,0 +1,70 @@
+<?php
+
+use PhpOffice\PhpSpreadsheet\Spreadsheet;
+
+require __DIR__ . '/../../Header.php';
+
+$category = 'Engineering';
+$functionName = 'ERF';
+$description = 'Returns the error function integrated between lower_limit and upper_limit';
+
+$helper->titles($category, $functionName, $description);
+
+// Create new PhpSpreadsheet object
+$spreadsheet = new Spreadsheet();
+$worksheet = $spreadsheet->getActiveSheet();
+
+// Add some data
+$testData1 = [
+    [0.745],
+    [1],
+    [1.5],
+    [-2],
+];
+
+$testData2 = [
+    [0, 1.5],
+    [1, 2],
+    [-2, 1],
+];
+$testDataCount1 = count($testData1);
+$testDataCount2 = count($testData2);
+$testData2StartRow = $testDataCount1 + 1;
+
+$worksheet->fromArray($testData1, null, 'A1', true);
+$worksheet->fromArray($testData2, null, "A{$testData2StartRow}", true);
+
+for ($row = 1; $row <= $testDataCount1; ++$row) {
+    $worksheet->setCellValue('C' . $row, '=ERF(A' . $row . ')');
+}
+
+for ($row = $testDataCount1 + 1; $row <= $testDataCount2 + $testDataCount1; ++$row) {
+    $worksheet->setCellValue('C' . $row, '=ERF(A' . $row . ', B' . $row . ')');
+}
+
+// Test the formulae
+$helper->log('ERF() With a single argument');
+for ($row = 1; $row <= $testDataCount1; ++$row) {
+    $helper->log(
+        "(C$row): "
+        . $worksheet->getCell('C' . $row)->getValue()
+        . ' The error function integrated between 0 and '
+        . $worksheet->getCell('A' . $row)->getValue()
+        . ' is '
+        . $worksheet->getCell('C' . $row)->getCalculatedValue()
+    );
+}
+
+$helper->log('ERF() With two arguments');
+for ($row = $testDataCount1 + 1; $row <= $testDataCount2 + $testDataCount1; ++$row) {
+    $helper->log(
+        "(C$row): "
+        . $worksheet->getCell('C' . $row)->getValue()
+        . ' The error function integrated between '
+        . $worksheet->getCell('A' . $row)->getValue()
+        . ' and '
+        . $worksheet->getCell('B' . $row)->getValue()
+        . ' is '
+        . $worksheet->getCell('C' . $row)->getCalculatedValue()
+    );
+}