Label generation; convert between .p8 __label__ and .p8.png actual labels
picotool can read and save "label" data from and to .p8 files. When a .p8 cart with label data is saved as a .p8.png, the label is discarded in favor of either the empty label or a label borrowed from a different .p8.png file.

Ideally, picotool would support full label generation when converting a .p8 to a .p8.png, including using a label image (if any) and generating the title and byline in the Pico-8 font on the label from the code. I'm not sure the title and byline features are worth the effort. A label-to-png routine could also be used for import/export of a PNG file as gfx data, so that might be worth figuring out.