The Wallet object used to have a guarenteed lifetime longer than the App
singleton, but then we started allowing people to delete their wallet
(argh!).
Also "external" modules, especially living outside of the main tree,
would be much more stable if they can avoid using raw pointers for core
concepts like the Wallet.
This sets up a basic system for creating modules on top of the flowee
pay static lib in a way that is ensured to be isolated (modules can't
accidentally use each other's classes)
The setup is made such that the buildsystem does the hard work on
plugging in a new module, making it so that all you need to do is create
a new dir and a "{something}ModuleInfo.h" file and it will get compiled
in.
The point there is to make it not have any merge conflicts and just make
it dead easy to get started.