v2.1.3 Support for custom data

[santoshlite]

• Fixed optimizers and more options to [customize expected returns and risk model] (https://github.com/ssantoshp/Empyrial/blob/3207c0de8d109db70bee8f9c8dbfa881cdeeb967/src/empyrial/main.py#L103)
• Support for custom data! data field has been added to the Engine class.
• Some code refactoring, get_report has been deleted. To generate a report, use empyrial(portfolio, report=True).

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This discussion was created from the release v2.1.3 Support for custom data.