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/ERFC.php

@@ -0,0 +1,42 @@
+<?php
+
+use PhpOffice\PhpSpreadsheet\Spreadsheet;
+
+require __DIR__ . '/../../Header.php';
+
+$category = 'Engineering';
+$functionName = 'ERFC';
+$description = 'Returns the complementary ERF function integrated between x and infinity';
+
+$helper->titles($category, $functionName, $description);
+
+// Create new PhpSpreadsheet object
+$spreadsheet = new Spreadsheet();
+$worksheet = $spreadsheet->getActiveSheet();
+
+// Add some data
+$testData = [
+    [0],
+    [0.5],
+    [1],
+    [-1],
+];
+$testDataCount = count($testData);
+
+$worksheet->fromArray($testData, null, 'A1', true);
+
+for ($row = 1; $row <= $testDataCount; ++$row) {
+    $worksheet->setCellValue('C' . $row, '=ERFC(A' . $row . ')');
+}
+
+// Test the formulae
+for ($row = 1; $row <= $testDataCount; ++$row) {
+    $helper->log(
+        "(E$row): "
+        . $worksheet->getCell('C' . $row)->getValue()
+        . ' The complementary error function integrated by '
+        . $worksheet->getCell('A' . $row)->getValue()
+        . ' and infinity is '
+        . $worksheet->getCell('C' . $row)->getCalculatedValue()
+    );
+}