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/ConfigSchema/schema/CSS.Proprietary.txt

@@ -0,0 +1,10 @@
+CSS.Proprietary
+TYPE: bool
+VERSION: 3.0.0
+DEFAULT: false
+--DESCRIPTION--
+
+<p>
+    Whether or not to allow safe, proprietary CSS values.
+</p>
+--# vim: et sw=4 sts=4