Merge pull request #567 from ianbarber/master

Fixed memory leak in stream engine
Fix mistaken use of xor in "2^31 - 1".
Merge pull request #568 from jmgao/patch-2

Fold constant expression into constant.
Make
    ./configure --with-system-pgm
detect the OpenPGM 5.2 system library.

Note that OpenPGM installs a versioned pkgconfig file
(openpgm-5.2.pc, openpgm-5.1.pc).
Merge pull request #569 from jpoliv/master

Make "./configure --with-system-pgm" detect the OpenPGM 5.2 system library.
refactored ZMQ_ROUTER_ANNOUNCE_SELF code. renamed it to ZMQ_PROBE_NEW_PEERS.
implement it for DEALER tocket.
+documentation
changed option name. +documentation changes
Fixed out-of-date reference
Packaging of ZMQ_PROBE

- Cleaned up man page a little
- Wrote test case tests/test_router_probe.cpp
Packaging on ZMQ_PROBE_ROUTER

- renamed to ZMQ_PROBE_ROUTER
Merge pull request #570 from hintjens/master

Packaging of probe function
Rename terminated->pipe_terminated
Minor cleanups
Implement ZAP and integrate it with PLAIN mechanism
Merge pull request #571 from hurtonm/master

Add ZAP support
Small fixes to documentation

- REQ and REP sockets don't have HWM issues
- ZMQ_DONTWAIT applies to DEALER and PUSH only
Updated ZAP request for changed protocol draft

- username and password sent as two string frames
- fixed test case to match
Merge pull request #572 from hintjens/master

Updated ZAP PLAIN request to follow latest draft
another iteration on ZMQ_PROBE_ROUTER
now it properly works for ROUTER
Merge pull request #573 from shripchenko/master

another iteration on ZMQ_PROBE_ROUTER