Version 2.3.0

• Add plot_ratio to the public API, which allows for making ratio plots between the histogram and either another histogram or a callable. #161
• Add .profile to compute a (N-1)D profile histogram. #160
• Support plot1d / plot on Histograms with a categorical axis. #174
• Add frequentist coverage interval support in the intervals module. #176
• Allow plot_pull to take a more generic callable or a string as a fitting function. Introduce an option to perform a likelihood fit. Write fit parameters' values and uncertainties in the legend. #149
• Add fit_fmt= to plot_pull to control display of fit params. #168
• Support <prefix>_kw arguments for setting each axis in plotting. #193
• Cleaner IPython completion for Python 3.7+. #179