Replace existing autoloader with Composer-supplied

- Move Friendica namespace to `src`
- Move required `ezyang/htmlpurifier` to vendor
- Remove existing static autoloader
- Change boot.php reference to the autoloader

vendor/ezyang/htmlpurifier/plugins/phorum/config.default.php

@@ -0,0 +1,57 @@
+<?php
+
+if(!defined("PHORUM")) exit;
+
+// default HTML Purifier configuration settings
+$config->set('HTML.Allowed',
+  // alphabetically sorted
+'a[href|title]
+abbr[title]
+acronym[title]
+b
+blockquote[cite]
+br
+caption
+cite
+code
+dd
+del
+dfn
+div
+dl
+dt
+em
+i
+img[src|alt|title|class]
+ins
+kbd
+li
+ol
+p
+pre
+s
+strike
+strong
+sub
+sup
+table
+tbody
+td
+tfoot
+th
+thead
+tr
+tt
+u
+ul
+var');
+$config->set('AutoFormat.AutoParagraph', true);
+$config->set('AutoFormat.Linkify', true);
+$config->set('HTML.Doctype', 'XHTML 1.0 Transitional');
+$config->set('Core.AggressivelyFixLt', true);
+$config->set('Core.Encoding', $GLOBALS['PHORUM']['DATA']['CHARSET']); // we'll change this eventually
+if (strtolower($GLOBALS['PHORUM']['DATA']['CHARSET']) !== 'utf-8') {
+  $config->set('Core.EscapeNonASCIICharacters', true);
+}
+
+// vim: et sw=4 sts=4