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.BlockWrapper.txt

@@ -0,0 +1,18 @@
+HTML.BlockWrapper
+TYPE: string
+VERSION: 1.3.0
+DEFAULT: 'p'
+--DESCRIPTION--
+
+<p>
+    String name of element to wrap inline elements that are inside a block
+    context.  This only occurs in the children of blockquote in strict mode.
+</p>
+<p>
+    Example: by default value,
+    <code>&lt;blockquote&gt;Foo&lt;/blockquote&gt;</code> would become
+    <code>&lt;blockquote&gt;&lt;p&gt;Foo&lt;/p&gt;&lt;/blockquote&gt;</code>.
+    The <code>&lt;p&gt;</code> tags can be replaced with whatever you desire,
+    as long as it is a block level element.
+</p>
+--# vim: et sw=4 sts=4