keep state across invocations

[lmamane]

In InfiniTime, is there a way for my screen (app) to maintain some state across invocations? E.g. for app settings, but also for a stopwatch/timer that can resume even if the user switched to another screen and back. I would just store the time point at which the stopwatch/timer started, and then recompute the elapsed/remaining time from the current time point when it is reopened.

[lmamane]

I managed to do it by adding a new controller just for my app, taking inspiration from the Timer app.

The controllers implementations live in src/components, the structure that holds them all is in src/displayapp/Controllers.h, and they are created / stored by src/displayapp/DisplayApp.{h,cpp}