improved invoices with new renderer (#306)

* added docx renderer and demo template
* added csv renderer and demo template
* added xlsx renderer and demo template
* added ods renderer and demo template
* added user calculator
* added invoice documentation

src/Invoice/Renderer/OdsRenderer.php

@@ -0,0 +1,47 @@
+<?php
+
+/*
+ * This file is part of the Kimai time-tracking app.
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace App\Invoice\Renderer;
+
+use App\Invoice\RendererInterface;
+use PhpOffice\PhpSpreadsheet\IOFactory;
+use PhpOffice\PhpSpreadsheet\Spreadsheet;
+
+class OdsRenderer extends AbstractSpreadsheetRenderer implements RendererInterface
+{
+    /**
+     * @return string[]
+     */
+    protected function getFileExtensions()
+    {
+        return ['.ods'];
+    }
+
+    /**
+     * @return string
+     */
+    protected function getContentType()
+    {
+        return 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet';
+    }
+
+    /**
+     * @param Spreadsheet $spreadsheet
+     * @return bool|string
+     * @throws \PhpOffice\PhpSpreadsheet\Writer\Exception
+     */
+    protected function saveSpreadsheet(Spreadsheet $spreadsheet)
+    {
+        $filename = tempnam(sys_get_temp_dir(), 'kimai-ods');
+        $writer = IOFactory::createWriter($spreadsheet, 'Ods');
+        $writer->save($filename);
+
+        return $filename;
+    }
+}