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.SafeEmbed.txt

@@ -0,0 +1,13 @@
+HTML.SafeEmbed
+TYPE: bool
+VERSION: 3.1.1
+DEFAULT: false
+--DESCRIPTION--
+<p>
+    Whether or not to permit embed tags in documents, with a number of extra
+    security features added to prevent script execution. This is similar to
+    what websites like MySpace do to embed tags. Embed is a proprietary
+    element and will cause your website to stop validating; you should
+    see if you can use %Output.FlashCompat with %HTML.SafeObject instead
+    first.</p>
+--# vim: et sw=4 sts=4