Add website to client repository

Closes #1567

The main reason I'm not simply merging Annika's PR is because this
way makes it clearer that I'm taking responsibility for all this
code, that it's mostly code I wrote, and also because it makes it
easier to ensure that none of the files have been changed.

(Not that I don't personally trust Annika, but I have something
resembling an obligation to users not to expose them to risks based
on personal trust.)

website/lib/htmlpurifier/HTMLPurifier/ConfigSchema/schema/HTML.FlashAllowFullScreen.txt

@@ -0,0 +1,11 @@
+HTML.FlashAllowFullScreen
+TYPE: bool
+VERSION: 4.2.0
+DEFAULT: false
+--DESCRIPTION--
+<p>
+    Whether or not to permit embedded Flash content from
+    %HTML.SafeObject to expand to the full screen.  Corresponds to
+    the <code>allowFullScreen</code> parameter.
+</p>
+--# vim: et sw=4 sts=4