problem: no way to send raw udp messages with zeromq.

Problem: name confl from windows.h, draft API decl in pch.

Problem: zmq_poller_destroy can segfault

Problem: msvc builds are misconfigured.

Problem: test send count too high for AppVeyor CI environment

Solution:
Reduce send count so that the test does not timeout on AppVeyor CI
environment and older Windows boxes.