Move crash handling to the application level and simplify class structure. Starting to try to take real advantage of the refactoring, to have generic crash handling. This also lets us initialize the app without needing all the self.attempt() wrappers, since now there's a good system-wide crash handler at the app level (not inside the shell instance). I didn't yet remove the attempt() method because we may have occasional uses for it (we still do, but in one place only). I also removed some extra class layers that weren't quite needed. Creating classes solely for the purpose of passing parameters makes the code (IMO) harder to understand, I kept getting lost in parts of the class hierarchy. I think these changes provide the same flexibility but with easier to follow code (less things to remember, basically). What I tried to do was to use argument passing instead of inheritance for all cases I saw where the inheritance wasn't really adding new functionality. In some cases, this actually allowed me to remove methods that were effectively duplicated in the subclasses.