For more general package(stacking, bagging, and more)

[Ikki Tanaka]

Need to show some test of stacking, bagging, and more.

Stacking tests are done, but bagging tests are not.

Bagging tests are easy because only sub-sampling training data and training models with that data is needed.

Several options are considered(i.e., argument at model definition(subsample=0.8), different parameter models, different random state models, ...)

If this is done, this package will be more general one of ensemble learning.