Fix undefined oembed properties

- Add Object\OEmbed class

src/Object/OEmbed.php

@@ -0,0 +1,50 @@
+<?php
+
+namespace Friendica\Object;
+
+/**
+ * OEmbed data object
+ *
+ * @see https://oembed.com/#section2.3
+ *
+ * @author Hypolite Petovan <mrpetovan@gmail.com>
+ */
+class OEmbed
+{
+	public $embed_url        = '';
+
+	public $type             = '';
+	public $title            = '';
+	public $author_name      = '';
+	public $author_url       = '';
+	public $provider_name    = '';
+	public $provider_url     = '';
+	public $cache_age        = '';
+	public $thumbnail_url    = '';
+	public $thumbnail_width  = '';
+	public $thumbnail_height = '';
+	public $html             = '';
+	public $url              = '';
+	public $width            = '';
+	public $height           = '';
+
+	public function __construct($embed_url)
+	{
+		$this->embed_url = $embed_url;
+	}
+
+	public function parseJSON($json_string)
+	{
+		$properties = json_decode($json_string, true);
+
+		if (empty($properties)) {
+			return;
+		}
+
+		foreach ($properties as $key => $value) {
+			if (property_exists(__CLASS__, $key)) {
+				$this->{$key} = $value;
+			}
+		}
+	}
+}