Dev/engine ashley

First pass at creating the model for flight. I've tried to design it in a way that easily saves and reloads the state of the flyers, but don't know about how useable it will be for the patterns. I've written a brief list of things I need to work on as next steps at the top of the code.

@maina @mswai @plevis please take a look and let me know if you see any issues :)

EDIT I'm using Java 11