issue #3713: Object::release() of debug version will check whether the object was in autorelease pool.
issue #3713: Adds AutoreleasePool::isClearing() for easily debugging memory issues. It only valid in DEBUG mode.
issue #3713: Modifies the scope of DEBUG macro in CCAutoreleasePool.h , contains(Object* obj) should be valid in RELEASE version too.
Merge pull request #5203 from dumganhar/iss3713-ref-patch

issue #3713: Object::release() of debug version will check whether the object was in autorelease pool.