Grouped bar charts

The new method ~.Axes.grouped_bar() simplifies the creation of grouped bar charts significantly. It supports different input data types (lists of datasets, dicts of datasets, data in 2D arrays, pandas DataFrames), and allows for easy customization of placement via controllable distances between bars and between bar groups.

Example:

.. plot::
    :include-source: true
    :alt: Diagram of a grouped bar chart of 3 datasets with 2 categories.

    import matplotlib.pyplot as plt

    categories = ['A', 'B']
    datasets = {
        'dataset 0': [1, 11],
        'dataset 1': [3, 13],
        'dataset 2': [5, 15],
    }

    fig, ax = plt.subplots()
    ax.grouped_bar(datasets, tick_labels=categories)
    ax.legend()