bring forward key.c/authfile.c some more:

support ed25519 keys (hostkeys and user identities) using the public domain
ed25519 reference code from SUPERCOP, see http://ed25519.cr.yp.to/software.html
feedback, help & ok djm@

correct test that kdf name is not "none" or "bcrypt"

convert memset of potentially-private data to explicit_bzero()

replace most bzero with explicit_bzero, except a few that cna be memset
ok djm dtucker

don't refuse to load Ed25519 certificates