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

Remove ZMQ_IDENTITY_FD socket option

Revert "linking fd to pipe identity via socket option"

This reverts commit fe3e8c5c.

Conflicts:
	include/zmq.h
	src/pipe.hpp
	src/session_base.cpp

This reverts commit 45c68154.

resolve #1292 ZMQ_IDENTITY_FD does not validate option_len

Remove int typedefs and use stdint.h for windows.

Implement a definitive cygwin target for libzmq.

Problem: incomplete definition of integer types

Firstly, only a few types are defined, leaving it hard for higher layers
to complete the set. Secondly, the code incorrectly tries to use ifndef
to avoid re-defining typedefs, which does not work in C.

Solution: define all types, unconditionally for all MSVC compilers.
Additionally, define ZMQ_DEFINED_STDINT that tells higher layers that we
already defined these integer types.

Fixed atomic API, which used 'bool'

Solution: increase settle time for bind/unbind tests

zmq_atomic_counter_dec returned a 'bool' value, yet this isn't
defined by standard, so causes compile errors in upstream code.

Solution: return an int that can be safely converted to bool if
needed by bindings.

Problem: need atomic reference counting in several projects

Solution: as libzmq already provides this across all platforms,
expose an atomic counter API. I've not wrapped atomic pointers,
though someone who needs this may want to do so.