Bitcoin backup helper

[GBKS]

@bddesign wrote a nice introduction and summary of this mini project right here. We also discussed it in the design review call yesterday, and there's more detail on the microsite.

Overall, there seems to be interest in exploring this project further. It started with a conversation on Slack that sparked the idea, we got good feedback at the Hackathon, and @danielnordh is working on related documentation (which is what started this in the first place). Seems like various signals are pointing towards this being a worthwhile effort to pursue.

I am creating this issue to have a central place to track the project idea.