Golang Support for SPZ

Hello!

I’ve implemented the SPZ file format in golang. No C-bindings are required.

All code is MIT and can be found here:
https://github.com/EliCDavis/polyform/tree/main/formats/spz

A demo showcasing the editing of a SPZ file can be found here:
https://bsky.app/profile/elicdavis.bsky.social/post/3lbasgy6ixk2r

I would love requests/suggestions for what you’d like to be able to do when editing your SPZ files!