Inochi needs APNG export

[p0nce]

Ideally streamed, but we do not have a procedural/lazy image concept like ae.utils.graphics had.

[p0nce]

Needed changes:

• Rationalize and make readable PNG output which hardcode a lot of stuff. If using an I/O stream directly it would probably be faster too.
• From there, add acTL chunk before first image
• add fcTL chunk with an easy dispose method
• encode all other images in fdAT chunk