This change adds the socket identity infomartion from the socket to the
zap frames. In doing this the ZAP is able preform different operations
based on different sockets. This is not compaitable with the current ZAP
RFC, but that can be updated. As the ZAP rfc is currently draft for I
did not change the version number.
Tests also modified and passing.
The use of binary for CURVE keys is painful; you cannot easily copy
these in e.g. email, or use them directly in source code. There are
various encoding possibilities. Base16 and Base64 are not optimal.
Ascii85 is not safe for source (it generates quotes and escapes).
So, I've designed a new Base85 encoding, Z85, which is safe to use
in code and elsewhere, and I've modified libzmq to use this where
it also uses binary keys (in get/setsockopt).
Very simply, if you use a 32-byte value, it's Base256 (binary),
and if you use a 40-byte value, it's Base85 (Z85).
I've put the Z85 codec into z85_codec.hpp, it's not elegant C++
but it is minimal and it works. Feel free to rewrap as a real class
if this annoys you.