[Backtesting] Main script for backtesting

[DanielNobbe]

Write main script for backtesting. Pretty straightforward. Should be similar to main.py, but use the backtesting engine instead of scheduling jobs.

• Load data as dataframe
• Initialise backtesting strategy and other necessary stuff
• Run backtest
• Plot backtest and report results. Can be into file, or into jupyter notebook. If using a notebook, make sure that it imports functions from a python file, since that offers us the flexibility of also using the script outside of a notebook. https://kernc.github.io/backtesting.py/ https://kernc.github.io/backtesting.py/doc/examples/Quick%20Start%20User%20Guide.html