overhaueld the API: Basically it's reverting the last API overhaul, so class extenders are instantiated again. That way we won't run into troubles with late static binding of PHP <5.3, can properly implement the interface in extenders and extenders can make use of per extendable object variables.
However to ease explicit invocation of specific extenders an extender() method has been added to the faces extendable.
Also a test case for easy benchmarking of faces has been added and extending single methods without an interface is possible with functions now.

 * added a new FacesRoot base clase which allows Extenders to access protected class properties
 * changed Extender Classes to be not instantiated. This makes reuseing code easier and avoids garbage collection troubles with PHP 5.2. Thus the extended methods are now invoked statically and get the Extendable object passed as function callbacks.
 * Extender Classes need not implement the extended interfaces any more, so the    function signature may differ (e.g. to add the passed $element). Instead they have to    declare their faces in the implementsFaces() method.
 * improved faces.inc inclusion method to be more robust

refactored the API to not use separate face objects for preserving namespace issues. This greatly simplifies everything, but burdens using modules to prevent naming collisions.

added testcase for that

added a destroy() method which allows to explicitely desroy the object - working around about the php 5.2 gc issues.