[noise] expected length of messages during handshake

[David Wong]

OK, I'm tired, re-reading Trevor's quote from the spec it says exactly
what I just said

> "Length fields: Applications must handle any framing or additional
length fields for Noise messages, considering that a Noise message may
be up to 65535 bytes in length. If an explicit length field is needed,
applications are recommended to add a 16-bit big-endian length field
prior to each message."

What really bugged me here on my first read is the word "Application"
which should really be "your noise implementation". The application
should not have to worry about framing of Noises messages. So I'll
suggest a change of word here.

In addition, when writing a Noise library, I expect it to be able to
communicate to other libraries for interoperability testing. I cannot
do that here.

My question: why is this not part of the spec? (A 2 byte length-field
is a minor addition.)

Apologies for the misunderstanding,
David