⬆️ 🔨 Upgrade Markdownify library.

The current version 2.0.0 (alpha) throws deprecated warning with
PHP7.1 and PHPUnit.
Upgrade the HTML to Markdown converter for PHP to the current
Markdownify 2.2.1.
Used composer to manage this library.

vendor/composer/installed.json

@@ -518,5 +518,63 @@
         "keywords": [
             "markdown"
         ]
+    },
+    {
+        "name": "pixel418/markdownify",
+        "version": "v2.2.1",
+        "version_normalized": "2.2.1.0",
+        "source": {
+            "type": "git",
+            "url": "https://github.com/Elephant418/Markdownify.git",
+            "reference": "0160677f04c784550dd10fd72fdf3994967db848"
+        },
+        "dist": {
+            "type": "zip",
+            "url": "https://api.github.com/repos/Elephant418/Markdownify/zipball/0160677f04c784550dd10fd72fdf3994967db848",
+            "reference": "0160677f04c784550dd10fd72fdf3994967db848",
+            "shasum": ""
+        },
+        "require": {
+            "php": ">=5.3.0"
+        },
+        "require-dev": {
+            "phpunit/phpunit": "^4.8"
+        },
+        "time": "2016-09-21T13:01:43+00:00",
+        "type": "lib",
+        "installation-source": "dist",
+        "autoload": {
+            "psr-4": {
+                "Markdownify\\": "src",
+                "Test\\Markdownify\\": "test"
+            }
+        },
+        "notification-url": "https://packagist.org/downloads/",
+        "license": [
+            "LGPL"
+        ],
+        "authors": [
+            {
+                "name": "Peter Kruithof",
+                "email": "pkruithof@gmail.com",
+                "homepage": "http://pkruithof.tumblr.com/"
+            },
+            {
+                "name": "Milian Wolff",
+                "email": "mail@milianw.de",
+                "homepage": "http://milianw.de"
+            },
+            {
+                "name": "Thomas Zilliox",
+                "email": "hello@tzi.fr",
+                "homepage": "http://tzi.fr"
+            }
+        ],
+        "description": "The HTML to Markdown converter for PHP ",
+        "homepage": "https://github.com/elephant418/Markdownify",
+        "keywords": [
+            "markdown",
+            "markdownify"
+        ]
     }
 ]