[task/acm-refactor] Refactor the ACM classes to have a common interface.

They are now refered to as cache drivers rather than ACM classes. The
additional utility functions from the original cache class have been
moved to the cache_service. The class loader is now instantiated without
a cache instance and passed one as soon as it is constructed to allow
autoloading the cache classes.

PHPBB3-9983

phpBB/includes/cache/driver/base.php

@@ -0,0 +1,24 @@
+<?php
+/**
+*
+* @package acm
+* @version $Id$
+* @copyright (c) 2010 phpBB Group
+* @license http://opensource.org/licenses/gpl-license.php GNU Public License
+*
+*/
+
+/**
+* @ignore
+*/
+if (!defined('IN_PHPBB'))
+{
+	exit;
+}
+
+/**
+* @package acm
+*/
+abstract class phpbb_cache_driver_base implements phpbb_cache_driver_interface
+{
+}