High level API

[AdrianEddy]

Initial rough idea for the high level API - definitely not it's final form and implementation yet, there's a lot to still implement here, but the basic examples do work already

I moved pf.rs into pf/mod.rs and separated out parameters.rs from it

There's a global Justfile that handles bundle creation, which needs to be included by the user. This would have to be downloaded by users separately from the repo (unless there's a way to know the path of the crate downloaded contents, but I don't think there is)