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/Entity/InvoiceDocument.php

@@ -0,0 +1,52 @@
+<?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\Entity;
+
+class InvoiceDocument
+{
+    /**
+     * @var \SplFileInfo
+     */
+    private $file;
+
+    /**
+     * @param \SplFileInfo $file
+     */
+    public function __construct(\SplFileInfo $file)
+    {
+        $this->file = $file;
+    }
+
+    /**
+     * @return string
+     */
+    public function getId()
+    {
+        $file = $this->file->getFilename();
+
+        return substr($file, 0, strpos($file, '.'));
+    }
+
+    /**
+     * @return string
+     */
+    public function getName()
+    {
+        return basename($this->getFilename());
+    }
+
+    /**
+     * @return string
+     */
+    public function getFilename(): string
+    {
+        return $this->file->getRealPath();
+    }
+}