optuna refactoring

[Darel13712]

solves #35

• optimize is refactored
• param_drid parameter renamed to param_borders
• new tests are significantly faster because they don't call optuna

[Darel13712]

Note to self:

• make sure that missing parameters are not initialized with default borders and are not optimized.
• add a docs page explaining what is being optimized when you pass or do not pass arguments, and what happens with initialized model parameters