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/library/HTMLPurifier/Printer/ConfigForm.js

@@ -0,0 +1,5 @@
+function toggleWriteability(id_of_patient, checked) {
+    document.getElementById(id_of_patient).disabled = checked;
+}
+
+// vim: et sw=4 sts=4