Works with GCC and most likely clang

Code cleanup - removing unused local

Clean up of metadata_t

resolve #1325 Alignment issue with zmq_msg_t on SPARC CPU

* There is no clear reason why the map should hold const std::strings
* This class is never derived, there doesn't seem to be a compelling
  reason to ever do so, so no need to make virtual members
* In general const member data is an anti-pattern, the *only* reason
  is to prevent assignability, and the accepted idiom for that is to
  to declare the assigment operator private. This change does so, and
  also prevents copy construction.

should be backported probably

Added socket option ZMQ_INVERT_MATCHING.

ZMQ_INVERT_MATCHING reverses the PUB/SUB prefix matching. The subscription
list becomes a rejection list. The PUB socket sends messages to all
connected (X)SUB sockets that do not have any matching subscription.

Whenever the option is used on a PUB/XPUB socket, any connecting SUB
sockets must also set it or they will reject everything the publisher
sends them. XSUB sockets are unaffected because they do not filter out
incoming messages.

Fix Windows build

Problem: commit afb24b53 broke ZMQ_STREAM contract

Symptom is that ZMQ_STREAM sockets in 4.1.0 and 4.1.1 generate zero
sized messages on each new connection, unlike 4.0.x which did not do
this.

Person who made this commit also changed test cases so that contract
breakage did not show. Same person was later banned for persistently
poor form in CZMQ contributions.

Solution: enable connect notifications on ZMQ_STREAM sockets using a
new ZMQ_STREAM_NOTIFY setting. By default, socket does not deliver
notifications, and behaves as in 4.0.x.

Fixes #1316

Problem: copyright statements are out of date

Solution: update for 2015

Fixes #1320

Remove more test_id2fd cruft

documentation clarification on pipe::write failure

When pipe::write succeeds, it takes control of the message's data buffer.
When it fails, it has not taken control. The caller should clean up the
message appropriately (msg::close).

Close messages that failed to send

pipe_t.write only takes control of the underlying message memory when it
succeeds. When it returns failure, we must close the message ourselves to
clean up that memory.

This patch is sponsored by FarSounder, Inc (farsounder.com)

fix typo in zmq_msg_gets documentation

Fix typo in zmq_msg_gets documentation

Add 'Peer-Address' property to connection metadata

std::map::insert() has always had range based insertion, removed
explicit loops.

Allows non-C/C++ based clients easy access to the peer's IP address via
zmq_msg_gets(&msg, "Peer-Address") instead of zmq_msg_get(&msg, ZMQ_SRCFD)
followed by calls to getpeername and getnameinfo

Try to clarify the intent of zmq_msg_gets() in documentation

Make alignment compiler directive

Fix. Use C++03 compatible way to align struct. (Build on MSVC)

#1299 break compiling with MSVC 2010.

Align inter-thread shared structures on cache-line granularity

Specifically ypipe_t specializations for msg_t and command_t.

Currently only supports platforms where posix_memalign is available.

Increase size of zmq_msg_t to 64 bytes

Increasing it would have at least two benefits -

* More messages would be 'VSM' messages, so it would reduce allocation
overhead a bit.
* Remove any chance of false sharing of things that are, by design,
pushed by value onto a ypipe_t<msg_t> which is shared between two threads.

The only downside I see is slightly increased memory consumption on memory
constrained applications.

- Full discussion of this rationale is part of issue #1295