Revert part of 5be6e329324fc8263de56167091754e27305917b,
AEAD_Mode::start now returns a value again. While not useful for any
current modes it allows future flexibility of presenting
protoocol-level concepts (eg, OpenPGP encryption) using the AEAD
interface.
Lost get_aead decl in revert
Add a param to Connection_Cipher_State so it knows which direction
processing is happening.
Don't force download over TLS as some browsers crank