⬆️ Update HTML Purifier library.

Updated HTML Purifier from 4.6.0 to 4.9.2 with better PHP7 compatibility.
Used composer to manage this library.

vendor/ezyang/htmlpurifier/maintenance/remove-trailing-whitespace.php

@@ -0,0 +1,37 @@
+#!/usr/bin/php
+<?php
+
+chdir(dirname(__FILE__));
+require_once 'common.php';
+assertCli();
+
+/**
+ * @file
+ * Removes trailing whitespace from files.
+ */
+
+chdir(dirname(__FILE__) . '/..');
+$FS = new FSTools();
+
+$files = $FS->globr('.', '{,.}*', GLOB_BRACE);
+foreach ($files as $file) {
+    if (
+        !is_file($file) ||
+        prefix_is('./.git', $file) ||
+        prefix_is('./docs/doxygen', $file) ||
+        postfix_is('.ser', $file) ||
+        postfix_is('.tgz', $file) ||
+        postfix_is('.patch', $file) ||
+        postfix_is('.dtd', $file) ||
+        postfix_is('.ent', $file) ||
+        $file == './library/HTMLPurifier/Lexer/PH5P.php' ||
+        $file == './maintenance/PH5P.php'
+    ) continue;
+    $contents = file_get_contents($file);
+    $result = preg_replace('/^(.*?)[ \t]+(\r?)$/m', '\1\2', $contents, -1, $count);
+    if (!$count) continue;
+    echo "$file\n";
+    file_put_contents($file, $result);
+}
+
+// vim: et sw=4 sts=4