Fixed zmq_errno function definition
Minor whitespace fixes in man page
Simplify ZMQ_STREAM socket implementation, part II
Merge pull request #595 from hurtonm/master

Another ZMQ_STREAM simplification
Updated security mechanisms to use variable-length commands

RFC23, RFC24, RFC26 now use variable-length command names that
end in null octet (valid C strings) instead of fixed-length
space padded strings.
Simplify ZMQ_STREAM socket implementation, part II
Return EINVAL when trying to use CURVE without libsodium
Merge pull request #596 from hintjens/master

Problem: mechanisms are lagging behind specs
Added Z85 support

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.
Use generic session class whenever possible
Merge pull request #598 from hurtonm/master

Use generic session class whenever possible
Use generic session class whenever possible
Make last_endpoint attribute of socket object
Merge pull request #599 from hurtonm/master

Minor code refactoring
Merge pull request #597 from hintjens/master

Problem: working with binary keys is painful
Set socket buffers before establishing TCP connection

The window scale option carried in SYN segment is computed from socket's
receive buffer size. So we need to set this buffer size before calling
connect or bind.
Merge pull request #600 from hurtonm/master

Set socket buffers before establishing TCP connection
LIBZMQ-541 issue fix
Check socket types during mechanism handshake
Merge pull request #602 from hurtonm/master

Implement socket type checking