Extending the trading engine

[kaz875]

Very well done @jarthursquiers.

Was looking for a google sheet based simple Robo-advisor and this one comes the closest. I'm not an option trader, but this code base seems to have good foundations for extension. Before I spent days and weeks, to avoid heading into a wrong path, it would be great to get your suggestions on how things look for extending this project to support the following:

• Support stock purchase (not just active quote alert monitoring) through TDA api
• Support ETFs in the portfolio instead of just options

Thanks!