git-send-email(1): Encrypted email

Hi!

When there's a vulnerability, many projects require that patches (and related discussions) are encrypted with the GPG keys of the maintainers.

It would be nice to be able to send such patches with git-send-email(1), which would have to use the GPG keyring (git(1) already has code to use the keyring, for example for git-commit(1) -S (--gpg-sign), so I guess it's not crazy to extend such use of the keyring to encrypt patches.

What do you think about it?

Thanks, Alex