PROJECT: Modular Bitcoin-Standup-Scripts

There is a PR to our Bitcoin Standup scripts from former internet @jodobear that modularizes these scripts to allow for additional open source bitcoin libraries to be chosen to install: https://github.com/BlockchainCommons/Bitcoin-Standup-Scripts/pull/15

That PR likely was entirely functional two years ago, but we let other priorities get in our way, and by the time we went back to the modular scripts they were out of date due to updates to the core script. So, the core idea is to figure out how to merge @jodobear's already great work with the repo as it stands now.

We'd also like to see a version tested against older versions of macOS (in particular Mojave) as the Gordian Server app doesn't work with these old releases, and there are some good reasons why to support Bitcoin-Core on old hardware (in particular Mac minis).

Beyond that, questions include:

* How can we create an interface that maximizes usability?
* Are there newer modules that we should add?
* How can we document why people would want to use (or not) all of these options?