Expose crate as lib

[gak]

I was hoping to use this crate as a lib, so I can write my own automation.

I'm happy to do it but it might be better suited in its own crate because of the -cli part of the name.

Also, a consumer of the lib might want async rather than blocking, but that can be added on later via features.

[gak]

Sorry I realise now that I'm much less inclined to do this work as I want async, and just want to hack together something quick and nasty.

Feel free to close!