Move HTML to Markdown library to Composer

vendor/league/html-to-markdown/src/Converter/TextConverter.php

@@ -0,0 +1,46 @@
+<?php
+
+namespace League\HTMLToMarkdown\Converter;
+
+use League\HTMLToMarkdown\ElementInterface;
+
+class TextConverter implements ConverterInterface
+{
+    /**
+     * @param ElementInterface $element
+     *
+     * @return string
+     */
+    public function convert(ElementInterface $element)
+    {
+        $markdown = $element->getValue();
+
+        // Remove leftover \n at the beginning of the line
+        $markdown = ltrim($markdown, "\n");
+
+        // Replace sequences of invisible characters with spaces
+        $markdown = preg_replace('~\s+~u', ' ', $markdown);
+
+        // Escape the following characters: '*', '_', '[', ']' and '\'
+        $markdown = preg_replace('~([*_\\[\\]\\\\])~u', '\\\\$1', $markdown);
+
+        $markdown = preg_replace('~^#~u', '\\\\#', $markdown);
+
+        if ($markdown === ' ') {
+            $next = $element->getNext();
+            if (!$next || $next->isBlock()) {
+                $markdown = '';
+            }
+        }
+
+        return $markdown;
+    }
+
+    /**
+     * @return string[]
+     */
+    public function getSupportedTags()
+    {
+        return array('#text');
+    }
+}