modified feedback for one click curve fitting

[svb688]

Added the ability to get feedback from all fit models, not just best one.

[longavailable]

Thanks for your interest.

The parameter feedback was designed to reuse the optimal model in a quick way. However, this is not recommended, since it's not sure if the returned optimal model is the really best. So all fitted models and figures were save in the curevefit directory, whether feedback is True or False explicitly.

It's better to look at the report before considering reusing the fitted models.

Last, if you are confident with one of the models or all models, you can reuse it/them easily. Check the example reuse_the_fitted_model.py.