Problem: accept4 not available on all platforms

Solution: check for availability in CMake and autoconf before using it

Problems: no NEWS for 4.2.3, missing some events docs, whitespace in header

Solution: add main features and bug fixes

Solution: add them

Solution: remove it

Problem: Build fails in Visual Studio 2008 without `stdint.h`

Problems: test_security_{zap|curve} often hangs, debian builds ignore test failures hiding issues

Solution: make test failures fail the build

Solution: set 0 linger on the sockets immediately after creating them
rather than immediately before closing them.
Running through helgrind/drd highlights a few race conditions, one of
which is the setting of linger vs checking it when closing the socket.
Work around it by setting it immediately to fix the test hangs.

Problem: test_stream_exceeds_buffer cannot be ran in parallel

Change zmq_recv to zmg_msg_recv since zmq_msg_t used there.

Solution: bind to wildcard and let the OS pick a free port instead
of using an hard-coded 12345 TCP port

add Haiku support

* link against libnetwork.so for network functions.

Problem: REQ socket with ZMQ_REQ_RELAXED does not report ZMQ_POLLOUT when queried for events after first message.

Problem: REQ socket with ZMQ_REQ_RELAXED does not report ZMQ_POLLOUT when queried for events after first message.

Solution: Check for strictness before returning false if no reply has been received.

Problem: Sometimes on OSX we get ETIMEDOUT instead of EAGAIN

Solution: Update errno value after calling usleep()

Optimize select on Windows; reduce code duplication in select_t

Solution: unified Windows & non-Windows code further

Solution: reduced code duplication by introducing local variables and
new function trigger_events

same fds

Solution: cache results of get_fd_family

Problem: wsa_events are initialized/destroyed within every loop

iteration even if not used

Solution: Move wsa_events closer to usage

Change ZMQ_THREAD_AFFINITY to ZMQ_THREAD_AFFINITY_CPU_ADD/REMOVE

Change ZMQ_THREAD_AFFINITY to ZMQ_THREAD_AFFINITY_CPU_ADD/ZMQ_THREAD_AFFINITY_CPU_REMOVE. Avoid prefix thread names when no prefix was set.

Partial Windows XP support

Problem: one missed optimization opportunity for blob_t map lookup

Solution: create referencing blob_t

Problem: use of std::map::insert is inefficient

Solution: use std::map::emplace instead, where available

Problem: description of return value is cloned from zmq_atomic_counter_new

Solution: provide correct description

Fixes #2789

* Problem: excessive memory allocations around blob_t

Solution: redefine blob_t as a custom type, and use reference/move
semantics where possible

* Clarify usage of zmq_close

Problem: comment before sndtimeo/rcvtimeo does not specify dimension