This patch allows client applications to retrieve the remote endpoint from a message that originated from a tcp socket

Update test_filter_ipc to not use abstract socket.

This fixes the test on Mac OS X and SmartOS (probably other Solarises).
Also updates the sockets using ipc: to use DEALER sockets instead
of PAIR sockets.

Fix LIBZMQ-576 - Revert "Merge pull request #510 from miniway/master"

This reverts commit f27eb67e, reversing
changes made to a3ae0d4c.

https://zeromq.jira.com/browse/LIBZMQ-576

Conflicts:
	src/stream_engine.cpp

Conflicts were around additional defaults to the constructor after the
'terminating' default.  The additional defaults were left alone, and
the 'terminating' default was removed.

Minor cosmetic fixes

- corporate copyright statements sit in AUTHORS file

- This seems redundant; is there a use case for NOT providing
  the IPC credentials to the ZAP authenticator?

- More, why is IPC authentication done via libzmq instead of ZAP?
  Is it because we're missing the transport type on the ZAP request?

- put into alphabetical order
- there was no consistency in previous ordering

Minor layout fix

Whitespace fix

fix doc typo

doc bugfix: ZMQ_MSGMORE should be ZMQ_SNDMORE

Fixed setting TCP keepalive parameters on Windows

Fixes to IPC wildcarding & test cases

- was not waiting long enough at socket close
- increased to 50 msec

Fixed use of deprecated tempnam

add failing test for binding to resources

Update doc for zmq_proxy_steerable [ci skip]

Add tests/test_zap_ipc_creds to .gitignore

Single connect

support signaler_port in config.hpp set to value other than 0 and 5905

tools/: Link curve_keygen with a c++ linker

When trying to linking curve_keygen as if it was a C program, linking
fails (at least with gcc 4.8 on Debian testing) because it can't find
C++ symbols. Linking with g++ instead fixes the issue.

To achieve this, the source is renamed to curve_keygen.cpp, and
tools/Makefile.am is updated accordingly.
Signed-off-by: Gergely Nagy <algernon@balabit.hu>

Add support for extending ZAP request address with IPC peer credentials.