[add] HTML Purifier added to clean code

inc/3rdparty/htmlpurifier/HTMLPurifier/ConfigSchema/schema/CSS.AllowedProperties.txt

@@ -0,0 +1,18 @@
+CSS.AllowedProperties
+TYPE: lookup/null
+VERSION: 3.1.0
+DEFAULT: NULL
+--DESCRIPTION--
+
+<p>
+    If HTML Purifier's style attributes set is unsatisfactory for your needs,
+    you can overload it with your own list of tags to allow.  Note that this
+    method is subtractive: it does its job by taking away from HTML Purifier
+    usual feature set, so you cannot add an attribute that HTML Purifier never
+    supported in the first place.
+</p>
+<p>
+    <strong>Warning:</strong> If another directive conflicts with the
+    elements here, <em>that</em> directive will win and override.
+</p>
+--# vim: et sw=4 sts=4