Naming inconsistencies after renaming options to settings

Regarding the algorithms, we dediced to rename options to settings and move n_samples and max_iter in these settings (these parameters are not options the last release).

This renaming should be cascaded for consistency and n_samples / max_iter should be considered as part of the settings.

For example,

• rename doe_algo_options to doe_algo_settings in MultiStart,
• rename opt_algo_options to opt_algo_settings in MultiStart,
• remove n_start (use doe_algo_settings for this concept),
• remove opt_algo_max_iter (use opt_algo_settings for this concept),
• move n_processes to doe_algo_settings

I think this inconsistency is present in many other classes.