Refactoring old apps to add new best practices

[CRImier]

Many apps contain old constructs that are no longer needed, but might be picked up as good practices by new contributors (or, in some cases, will prevent the app from working at all - though unlikely because generally backwards compatibility is preserved). So, refactoring those would help.

Old and outdated practices include:

• [ ] Using Printer(ffs(string, o.cols)) instead of PrettyPrinter(string)
• [ ] Using init_app in function-based apps just to set i and o (can be removed entirely in that case)
• [ ] Redefining __init__ in class-based apps just to set self.menu_name (can be removed entirely in that case)
• [ ] Not defining callback in function-based apps as a separate function
• [ ] Defining the main_menu inside init_app and using a global to access it from callback
• [ ] Adding ["Exit", 'exit'] entries to Menu elements (entry can just be removed)

All of these ought to be grepped for, then removed/replaced - afterwards, it's best if you test your changes by actually launching the app and confirming that it behaves the same way as it did previously.

[LouisPi]

I should be able to help out with this.

[CRImier]

Thank you!