There was doublewrapping with an unneeded msgio. given that we
use a stream muxer now, msgio is only needed by secureConn -- to
signal the boundaries of an encrypted / mac-ed ciphertext.

Side note: i think including the varint length in the clear is
actually a bad idea that can be exploited by an attacker. it should
be encrypted, too. (TODO)

License: MIT
Signed-off-by: Jeromy <jeromyj@gmail.com>