abTEM/abTEM ? reverse-engineered prompt

Build me a Python package called abTEM that lets users simulate transmission electron microscopy images and diffraction patterns from atomic structures.

I want the library to support both regular TEM and scanning TEM style simulations, with the main approaches being multislice and PRISM. It should work smoothly with atomic structures from ASE, and if possible use electrostatic potentials from GPAW when they are available. Make it easy to install with pip, easy to import, and simple enough that someone can start from a small example and get a realistic simulated image or diffraction pattern.

Please include clear docs or example scripts for getting started, a few basic tests, and a clean structure that feels like a real scientific Python package. If you need to look up current docs online for ASE or GPAW details, go ahead and do that.