Modify create_classifier to return shared_ptr
Modify create_storage to return shared_ptr
Clarify classifier_base has ownership of storage_base
Modify create_regression to return shared_ptr
Clarify regression_base has ownership of storage_base
Modify create_anomaly to return shared_ptr
Modify create_graph to return shared_ptr
Modify create_recommender to return shared_ptr
Modify create_norm to return shared_ptr
Modify create_nearest_neighbor to return shared_ptr
Modify create_key_matcher to return shared_ptr
Remove unnecessary scoped_ptr
Modify num_feature_factory::create to return shared_ptr
Modify num_filter_factory::create to return shared_ptr
Modify splitter_factory::create to return shared_ptr
Modify string_filter_factory::create to return shared_ptr
Fix memory leak on exception
Merge pull request #430 from gintenlabo/clarify-pointer-ownership

Clarify pointer ownership (fix issue #395)