Escape story fields and clean story HTML with HTML Purifier.

Add HTML Purifier 4.19.1. Stories are purified when they are saved and
when they are shown.

lib/htmlpurifier-4.19.1/library/HTMLPurifier/Exception.php

@@ -0,0 +1,12 @@
+<?php
+
+/**
+ * Global exception class for HTML Purifier; any exceptions we throw
+ * are from here.
+ */
+class HTMLPurifier_Exception extends Exception
+{
+
+}
+
+// vim: et sw=4 sts=4