Add Themizer to master

Synopsis
=======

This pull request merges the themizer part of EvDo into master.

WARNING
========

Due to PDO work on `master` and Themizer work on `themizer`, these branches cannot be automatically merged. Here is a list of files that will have to be manually merged:

- error/403.php
- error/404.php
- error/410.php
- error/418.php
- error/500.php
- include/db.php
- include/header.php
- admin.php
- database.php
- forgot.php
- index.php
- myaccount.php
- mysettings.php
- register.php
- themizer.php