Problem: Private/internal macros defined in public header.

Solution: Move the macros to a private header.

rename ZMQ_UNUSED macro to LIBZMQ_UNUSED

Fix zmq crash when calling shutdown with a pending inproc socket connect

Set signaler_port to 0 which allows the OS to find a free port

-Set signaler_port to 0 which allows the OS to find a free port, rather than crashing if 5905 is in use (https://github.com/zeromq/libzmq/issues/1542)
-Added config.hpp to the source list so it shows up in generated projects
-Remove CMAKE_BUILD_TYPE setting for generators that don't use it

Problem: Source files contain mixed tabs and spaces.

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

Fixes failing tests regarding XPUB sockets.

Fixes tests that were introduced in a previous pull request. See
https://github.com/zeromq/libzmq/pull/1539#issuecomment-132968987

Addresses zeromq/libzmq#1116.

This patch  adds a new member of type deque to the
xpub class that contains pointers to metadata_t.
This deque is then used (alongside pending_data
and pending_flags) to preserve metadata when
copying messages.

CI run on OSX needs binutils

problem: trying to support polling on thread safe sockets with zmq_poll failed

OSX does not ship with binutils, need to install it before the script
run via brew in order to be able to use greadelf, needed by the
qt-android CI script.

problem: new poller field in zmq_pollitem_t is changing the api

Problem: tests fail after PR #1531

apply a change to LIBZMQ_DELETE macro (related to issue #1524)

define a macro for heap object deletion in a unified manner (related …

Container-based CI build

CI build does not fail when tests fail. Fix #1527

problem: new field is breaking existing code

problem: user cannot poll on thread safe sockets