Version 0.3.0

• Renaming estimators.py module to regression.py
• New classification.py module with MapieClassifier class, that estimates prediction sets from softmax score
• New set of unit tests for classification.py module
• Modification of the documentation architecture
• Split example gallery into separate regression and classification galleries
• Add first classification examples
• Add method classification_coverage_score in the module metrics.py
• Fixed code error for plotting of interval widths in tutorial of documentation
• Added missing import statements in tutorial of documentation
• Refactorize tests of n_jobs and verbose in utils.py