clean up

more sensible naming.

Calling something a key-pair usually implies public/private. It's awkward
to use it to refer to encryption/decryption. Instead, encryption and
decription keys together are now called Keys. Apart, they're called
subKeys. And a full set (encryption, decryption, public, and private) is
now called a KeyPair.

I also added some convenience functions.

fix tests

more sensible naming

more stable serde

bump and better coverage

add benchmark
upgrade hermeti to take advantage of PipeInFiles()
remove cruft

add runnable example, but try to make it actually runnable

add runnable example, but try to make it actually runnable

add runnable example

even smaller smaller smaller container image

even smaller smaller container image