…n new code after underline changes related to data pack. After discussed with Hector using standard LRU_Cache instead of custom cache.

… created an non-cached version of get_class (get_class_nc) and used in get_class to avoid dynamic list issue as mentioned in comments of asyml#765 as pointed out my Hector.

…at have optional list as parameter -- change to cache lower level result from "locate" method called in this method, and also provide a non-cached version (same as before) for resolving asyml#765.

…e-factoring into one method with "cached_lookup" optional flag -- by default this is true but in _get_sub_class this flag needs to set to "false" based on comments in asyml#765 (for dynamic class loading scenario).