Solution: Provide poll() for Windows as well. This is a build option that
defaults to off as the resulting binary will only run on Windows Vista or
newer.

This is not tested with alternative Winsock service providers like VMCI,
but the documentation for WSAPoll does not mention limitations.

On my local machine, throughput improves by ~10 % (20 simultaneous
remote_thr workes to one local_thr, 10 byte messages), while latency
improves by ~30 % (measured with remote/local_lat).

Solution:
- Add checks for **poller_p_ to ensure that we do not segfault when either it
  or the value within it are NULL
- Add tests for the above and increase error state coverage

Solution:
Wrap and clean it.

Solution:
- Add check for the [count] parameter in zmq_sendiov() and zmq_recviov()
- Use and add test for zmq_sendiov() in tests/test_iov.cpp
- Add error state tests for zmq_sendiov() in tests/test_iov.cpp
- Add error state tests for zmq_recviov() in tests/test_iov.cpp
- Cleanup tests/test_iov.cpp for style, consistency and clarity
- Generally improve test coverage for both API methods

Hat-tip:
@somdoron, @bluca

Solution: fix it

Solution: use zmq_assert to ensure it's not a nullpointer

Solution: fix it

Solution: The Coverity Static Code Analyzer was used on libzmq code and found
many issues with uninitialized member variables, some redefinition of variables
hidding previous instances of same variable name and a couple of functions
where return values were not checked, even though all other occurrences were
checked (e.g. init_size() return).

Solution: Phase I - make precompiled.hpp be first file included in every source file

It's unclear which we need and in the source code, conditional code
treats tweetnacl as a subclass of libsodium, which is inaccurate.

Solution: redesign the configure/cmake API for this:

* tweetnacl is present by default and cannot be enabled
* libsodium can be enabled using --with-libsodium, which replaces
  the built-in tweetnacl
* CURVE encryption can be disabled entirely using --enable-curve=no

The macros we define in platform.hpp are:

    ZMQ_HAVE_CURVE    1        //  When CURVE is enabled
    HAVE_LIBSODIUM    1        //  When we are using libsodium
    HAVE_TWEETNACL    1        //  When we're using tweetnacl (default)

As of this patch, the default build of libzmq always has CURVE
security, and always uses tweetnacl.

And I'm on a reasonably sized laptop. I think allocating INT_MAX
memory is dangerous in a test case.

Solution: expose this as a context option. I've used ZMQ_MAX_MSGSZ
and documented it and implemented the API. However I don't know how
to get the parent context for a socket, so the code in zmq.cpp is
still unfinished.

Solution: be more explicit in the code, and in the zmq_recv man
page (which is the most unobvious case). Assert if length is not
zero and buffer is nonetheless null.

It's undefined behavior, and ubsan flags it.

Solution: update to 2016

Solution: include climits

Fixes #1720

to avoid overflow for large messages

send/recv still succeed for large messages,
but `zmq_msg_size` must be used to get the true size.

These sockets don't handle multipart data, so if callers send it,
they drop frames, and things break silently.

Solution: if the caller tries to use ZMQ_SNDMORE, return -1 and
set errno to EINVAL.

Solution: add these

Solution: change zmq_poller_close(p) to zmq_poller_destroy(&p)

If we're going to add CLASS-like APIs we should use the proper
syntax; specifically 'destroy' instead of 'close', which is a
hangover from the 'ZeroMQ is like sockets' model we're slowly
moving away from.

Solution: change zmq_timers_close(p) to zmq_timers_destroy(&p)

VMCI transport allows fast communication between the Host
and a virtual machine, between virtual machines on the same host,
and within a virtual machine (like IPC).

It requires VMware to be installed on the host and Guest Additions
to be installed on a guest.

We do not use 'get' for getters.

Solution: rename to zmq_msg_routing_id () for public API.

Solution: Move the macros to a private header.

Solution: Convert to spaces and remove trailing whitespace in these files.