Empyrial Versions Save

• Fixed optimizers and more options to customize expected returns and risk model
• Support for custom data! data field has been added to the Engine class. Check the doc here to learn how to use it: https://empyrial.gitbook.io/empyrial/
• Some code refactoring, get_report has been deleted. To generate a report, use empyrial(portfolio, report=True).

Quick fix

Fixed TypeError that occurs when a default value (current date) is passed to the Engine.

#77 and #104 fixed, credit goes to @pzzhang