GetNextInPersistentObject

// Get the next object within oPersistentObject.
// - oPersistentObject
// - nResidentObjectType: OBJECT_TYPE_*
// - nPersistentZone: PERSISTENT_ZONE_ACTIVE. [This could also take the value
//   PERSISTENT_ZONE_FOLLOW, but this is no longer used.]
// * Returns OBJECT_INVALID if no object is found.
object GetNextInPersistentObject(object oPersistentObject=OBJECT_SELF, int nResidentObjectType=OBJECT_TYPE_CREATURE, int nPersistentZone=PERSISTENT_ZONE_ACTIVE);