Rename to model_selection, GridSearchCV and LineSearchCV

[lbluque]

Summary

• rename 'optimizer.py' to 'model_selection.py' to follow scikit-learn more closely.
• rename GridSearch to GridSeachCV for more explicit naming.
• rename GridSearch to LineSeachCV for more explicit naming.

Checklist

• Code is in the standard Python style.
  Run pycodestyle and flake8
  on your local machine.
• Docstrings have been added in the Google docstring format.
  Run pydocstyle on your code.
• Tests have been added for any new functionality or bug fixes.
• All existing tests pass.

[qchempku2017]

I prefer not to rename these classes because these classes are not only implemented to use the one standard error rule selection. OneSE is just an option for them. It's not very necessary to change the naming.

[lbluque]

I prefer not to rename these classes because these classes are not only implemented to use the one standard error rule selection. OneSE is just an option for them. It's not very necessary to change the naming.

Ah ok that makes sense. Then I think we should find a name that is descriptive to the class (perhaps it should have "CV" in there bc that's what it's basing the optimization, right?), or perhaps just name it the same as sklearn GridSearchCV, but then I think it's confusing what the difference between the one here is.

Any suggestion?

[lbluque]

renamed to GridSearchCV and LineSearchCV