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/HTML.Nofollow.txt

@@ -0,0 +1,7 @@
+HTML.Nofollow
+TYPE: bool
+VERSION: 4.3.0
+DEFAULT: FALSE
+--DESCRIPTION--
+If enabled, nofollow rel attributes are added to all outgoing links.
+--# vim: et sw=4 sts=4