This adds support for verification of ed25519 certificates according to
RFC 8410. Implements #49.
The test certificate was generated using OpenSSL 1.1.1a, using the
following commands (CA.pl is distributed with OpenSSL):
openssl genpkey -algorithm ed25519 -outform pem -out root_key.pem
openssl req -new -x509 -days 9999 -extensions v3_ca -key root_key.pem \
-inform pem -outform pem -out root_ed25519.pem
echo root_ed25519.pem | CA.pl -newca
openssl genpkey -algorithm ed25519 -outform pem -out client_key.pem
openssl req -new -key client_key.pem -inform pem -outform pem \
-out client_ed25519_csr.pem
openssl ca -keyfile ./root_key.pem -days 999 -notext -in \
client_ed25519_csr.pem -out client_ed25519.pem
I agree to license my contributions to each file under the terms given
at the top of each file I changed.