The log server now advertises a subcommands flag if it supports
logging subcommands (e.g. commands run from a sudo-spawned program
like a shell). The client should only log additional commands
during a session if this flag is set in the ServerHello message.
This makes it easier to detect a plaintext client sending to a
TLS port. Without this, the TLS server will be silent as it
waits for the client to initiate the TLS connection.
For TLS connections we now do the TLS handshake immediately before
the ServerHello message. This lets the client recieve an alert
from the server is there is a handshake error after the TLS connect
has succeeded. It also means that the contents of the ServerHello
are protected from a man-in-the-middle attack.
