Fix issue #335

The CreateEvent function requests EVENT_ALL_ACCESS access rights
when the event object already exists. This causes problems
when the event object is created from a service.
The solution is to call OpenEvent function when the CreateEvent
failed due to access control.
The proper solution would be to use CreateEventEx function, but
this one is not available on Windows XP.

C++ style comments result in compile errors with non-c99 C compiler

Handle ETIMEDOUT

Implement ZMQ_TCP_KEEPALIVE* family of options to adjust TCP keepalives

currently not fully cross-platform
work on linux
possibly work in *bsd
and could be enhanced to work on windows

Fix identity exchange for inproc transport

The socket connecting using the inproc transport never
received the identity of the remote peer.

Flush identity message for inproc transport

The scoket implementation for inproc transfer failed to flush
identity message. The result was that the identity message
was not delivered until after the user sent the first message.

The identity message was never delivered if the user
used the socket only to receive messages.

Fixed issue #351

Fix error in router socket introduced in the previous commit

router: always respect message boundaries

router: reimplement peer identification

The current implementaion of router socket does not
handle the full pipe and unroutable messages properly.
Namely, in those cases, the socket could route some
message parts into a wrong connection.

The new implementation allows one to send messages through
a router socket to a peer even before receiving
messages from this peer.

Fixes issue #304

Added checking to zmq_ctx_set()

Fixed issue (unknown) on zmq_init(-1)

Code cleanup

Fix return value of send for router socket

It is the job of the posix_assert macro to check
the value. No need to do it twice.

The patch also fixes some whitespace problems.

The method is not used anymore.

The check_write method does not use the passed message.
The parameter was needed to implement the swap.
As the swap is not supported anymore, it is safe to remove this parameter.

Tcp address fixes anc cleanups

This still rejects 00 as port number.

Fixed issue LIBZMQ-348 - Valgrind support

Fix for issue #307

Don't set the AI_V4MAPPED flag on FreeBSD