negotiateKexName

string negotiateKexName(scope  const  SshKexInit client,
       scope  const  SshKexInit server)

@safe

Negotiates only the key-exchange name from both KEXINITs.

`client`	Our KEXINIT.
`server`	The server's KEXINIT.

The first client preference the server also lists (indicator

names skipped), or an empty string when nothing matches.