Added Propellor.Property.Installer modules, which can be used to create
bootable installer disk images, which then run propellor to install a
This code was extracted from the demo I gave at my talk at DebConf 2017,
from the secret-project repository. That repository was AGPL licensed.
I hereby relicense the code committed here under the same 2-clause BSD
license as the rest of propellor.
Changes from secret-project: Generalized UserInput to a type class,
and added a lot more documentation and examples.
This commit was sponsored by Brock Spratlen on Patreon.