Remove uses of apply_with_arguments API in reflection

Instead of ZEND_HASH_FOREACH. As a side-effect, this fixes a latent
bug in _addmethod, where a zval was interpreted as a zval*.

Also apply some optimizations to getProperties() while at it: For
declared properties, use the HT key instead of unmangling the
property name. For dynamic properties check INDIRECT instead of
looking up prop info to determine if the property is dynamic.