v2.0.1

Features

• Allow colors in ColorMixin to be nullable. (2db988b)
• Remove constraint on number of x_labels for Variable. (c42b906)
• Add support for secondary and tertiary color in ColorMixin. (2cb038f)
• Allow empty data source in DataSourceMixin. (0ae6fbd)
• Update into notebook. (0b8db6b)

Fixes

• Fix test requirements. (ae0da66, f96b6de)