california_housing

- Even if hyperparameters file is ignore with skip_best_hyperparams option, still use the same forest_size to be comparable;
- Update experiment files for stage1 wo_param experiments (using the same forest size as the with_params experiments);
- In compute_results: remove useless folder creation; temporary add extracted_forest_sizes_number option to specify the extracted forest sizes number; temporary not plotting train and dev losses in stage1 loss values figure;
- In plotter, clean-up stage1 figure generation;
- Add first unbiased losses plot (stage1: best params vs default params in california housing dataset).