All module paths should be absolute, not relative to drupal root. See https://drupal.org/node/2162691

Fix autoload stack order in XAutoloadUnitTestCase, if the non-apc loader was registered in bootstrap.

Introduce a CommonRegistrationinterface for class finder and adpater, so they now share the most common registration operations like addPsr0(), addPsr4(), etc.

PHPUnit tests for class finding and class loading, the latter based on StreamWrapper instead of fixtures.

Let xautoload(NULL) return the service container, to allow a syntax like xautoload(NULL)->finder, with full type hinting and stuff

Only activate APC if drupal_hash_salt is available. This will make it possible to use xautoload.early.php outside of Drupal, e.g. in phpunit.