major behavior changes: (made in openssh master tree - openbsd usr.bin/ssh)
- ssh(1) now defaults to ssh protocol version 2.
if you want version 1 to take precedence, use /etc/ssh.conf to override.
- config change: ~/.ssh/id_rsa[12] is now ~/.ssh/id_rsa (changed 4/3)
- forced client rekey for protocol version 2 (~R)
- swap gid when uid swaps.
- ListenAddress syntax can take [foo]:port for IPv6 numerics.
- "ssh -D 1080" allows us to use ssh tunnel as SOCKS4 proxy.
