initial add of attachment reading utility
This is a quick and dirty tool to detach an attachment as specified here:
https://nullprogram.com/blog/2021/12/31/
It uses pypng for the interesting bits.
To try it out:
poetry install
poetry run png-detach atch-test.png
Any original code in this project is offered under the MIT license. See LICENSE.md for details if it's not immediately obvious to you what that means and you want to use this for some reason.