[ClassLoader] Added an ApcClassLoader
[ClassLoader] Added an ApcClassLoader

Unlike the ApcUniversalClassLoader, ApcClassLoader uses composition,
meaning it can be used to wrap any object providing a findFile($class)
method. Both the UniversalClassLoader and the new ClassLoader follow
this convention. It can also be used to wrap the Composer autoloader.

symfony/class-loader,cyrrill/loader,symfony/ClassLoader,oswaldderiemaecker/ClassLoader