zmq_curve_keypair(): return result from crypto_box_keypair()

Problem: refactor gone wrong, redundant thread name

Solution: call it simply "ZMQ background" instead of "ZMQ b/g thread"

Solution: fix ifdef check for pthread_setname

Problem: ZMQ background threads are unnamed

Solution: use pthread API to set the name. For now call every thread
"ZMQ b/g thread". Would be nice to number the I/O threads and name
explicitly the reaper thread, but in reality a bit of internal API
churn would be necessary, so perhaps it's not worth it.
This is useful when debugging a process with many threads.

problem:zmq_poll is slow and the API is complicated

solution: deprecate zmq_poll in favor of zmq_poller

problem: zmq_poll is slow because FD is being created on every call

making the creation of FD only when thread safe sockets are in used
within the zmq_poller which improve the zmq_poll performance.

Problem: zmq::signaler_t::send may loop forever

Solution: restore the wsa_assert statement previously removed.

Problem: Travis using deprecated OBS project

Solution: switch to shiny new one in the network:messaging namespace

Problem: Assertion failed in zmq::signaler_t::send

Solution: Change to the way it does below on non-Windows platforms, retry when send returns -1.

Problem: router pipe can block forever

Solution: invert check_write and check_hwm calls in router xsend
function so that check_write can mark the pipe as inactive if
necessary.

Problem: unnecessary change to router_mandatory_hwm test

Solution:

Revert "Problem with ZMQ_ROUTER_MANDATORY option when peer lost"

This partially reverts commit 06740b5d.

The change in the mentioned commit was fixed to be backward
compatible so test changes are no longer necessary.
Partially revert the commit, leaving only the bug fix and taking out
the test change and the superfluous change in socket_base.

Commit: Issue #2348

indention

Revert "indention"

This reverts commit a6e7e192ac2d089ac9f7dc0d31d4b1fd10de982e.

indention

indention

Fix Failure in tests

Check both pipe full and pipe close

Problem: typo in the zmq_socket doc

Solution: fix it

* cmake WITH_LIBSODIUM option is broken

- Fixed the variable name in platform.hpp.in
- Fixed #if check for randombytes_close() when libsodium is used

* Fixed typo from previous commit

* Reverted compile error fix for randombytes_close()

#2341 fix

the root path name specified in this file cause the #2341 problem, the root path name is not need.

Problem: 4.2.2 is out, version(s) are out of date

Solution: bump changelog, ABI revision, library and packaging version

Problem: NEWS not up to date, packaging versions not up to date

Solution: bump to 4.2.2

Solution: mention main changes and bug fixes since 4.2.1

Problem: v4-in-v6 mapped addresses cause parsing failure

Include FindSodium.cmake in dist tarball

Solution: in the address validator accept an endpoint that starts
with :, eg: ::ffff:192.168.0.1:12345 as it's a valid mapped
address.

Problem: polling does not work well OOB in OpenIndiana

Solution: even though epoll() semantics are supported in modern illumos, it may differ from what Linux developers are used to expect. Skip epoll and use poll or select semantics (both were checked to work well).

fix divide by zero in zmq::lb_t::sendpipe