Proposal: Streaming Ed25519 verification

[paragonie-scott]

To reduce the memory requirements for Ed25519 verification, we use a streaming API to calculate the same result. I'm not confident that this should be included in v0.3.0, but some projects may desire this if v1.0.0 is ever tagged.

[paragonie-scott]

@dd32 indicated that WordPress would absolutely want this for WP providers that are just barely scraping by with their memory limits. In the future, I'll look into adding streaming auth(), box(), box_seal(), secretbox(), and their respective open/verify API methods. No promises that it will land in v1.0.0!

[dd32]

It wouldn't be a deal-breaker for WordPress, but the option would be greatly appreciated by others I'm sure.
When dealing with signatures, signing a file without having to pull the contents into memory first just seems expected (to me).

[paragonie-scott]

That's why I wrote ParagonIE\Halite\File :)

Okay, I'm going to do a quick internal code review then tag v0.3.0 and focus on #8 -- if you know anyone at Automattic to talk to about that, please send them my way.