Add end condition; Add misc enhancements

[mfraser4]

With this commit, a GameState enum is created to represent the different stages of the game. This variable is used as a reference for the main run loop to decide whether or not to keep running. A mock win screen has been created as a placeholder for another commit to actually implement it.

Other technical debt has been resolved, ranging from eliminating some magic numbers to creating an app feedback messages file to extract magic strings.

Technical debt created includes:

• Adding the win screen to app.py required importing new modules. Perhaps refactor loading_screen.py to be a general module that allows for the game to switch between panes conveniently.

resolves #12

[Neunis]

Looks good, nicely done.

In a way having the winpane display is nice if our users are able to learn and complete that many orders. If we had more time a cool idea would be to add a timer for if they reach X amount of orders before its too late and then the winpane pops-up; less education, gamier, and currently irrelevant.

What is relevant from that divergence is the number of cases to determine if they truly are educated winner, i.e. did they learn, or will it be a recognition of a pattern (which is still learning to an extent). I think if they get through that many cases, they hopefully have the gist of it.

Way to work magic once again and clear up some magic numbers and create modules respectively. Love it!

You have clearance from me to push to master.

[dvasavda]

Just added game_won.jpg to be more relevant.

[Neunis]

Glad we could hash ; ) that one out. Well done, crew.