Better libcrypto error messages.

Suggested by:	Mathieu Arnold
-fno-strict-aliasing is understood by both gcc and clang.
add support for SSHFP with ECDSA and SHA-256
Support ECDSA and SHA-256 in SSHFP.
Add support for SHA-384 digests in DS (RFC 6605).

Reported by:	mat
Merge remote-tracking branch 'tobez/master'

Conflicts:
	sshfp.c