Fix too long underline in zmq_ctx_set_monitor() docs

Rename monitor documentation source file to match zmq_ctx_set_monitor() API

Moves the monitoring infrastructure to a global zmq_ctx_set_monitor () API to avoid strict aliasing issues with function pointers and socket options.

Fixed bogus reference to zmq_ctx_put

Doc improvement: document interface omission in zmq_pgm.txt

Solaris/SunCC build fix: could not find a match for std::multimap<...>::insert(std::pair<...,...>)

The PGM transport supports the omission of the network interface to
select the default one like:

  announce.connect("epgm://eth0;239.255.128.46:64646"); // Use eth0
  announce.connect("epgm://239.255.128.46:64646"); // Use the default

Also, mention C++ in the additional community bindings of 0MQ in
zmq.txt.

Rename type zmq_monitor_fn -> zmq_monitor for a more natural callback definition API (zmq_monitor type, monitor.function callback)

Change zmq_monitor_fn type to cast between pointer-to-object and pointer-to-function in a more standards compliant way

Allow the ZMQ_MONITOR code compilable on gcc 4.7 on Linux.

The current ZMQ_MONITOR code does not compile in gcc 4.7, as -pedantic
and -Werror are enabled, and ISO C++ doesn't allow casting between
normal pointers (void*) and function pointers, as pedantically their
size could be different. This caused the library not compilable. This
commit workaround the problem by introducing one more indirection, i.e.
instead of calling

    (void *)listener

which is an error, we have to use

    *(void **)&listener

which is an undefined behavior :) but works on most platforms

Also, `optval_ = monitor` will not set the parameter in getsockopt(),
and the extra casting caused the LHS to be an rvalue which again makes
the code not compilable. The proper way is to pass a pointer of function
pointer and assign with indirection, i.e. `*optval_ = monitor`.

Also, fixed an asciidoc error in zmq_getsockopt.txt because the `~~~~`
is too long.

Expose a ZMQ_MONITOR socket option to register a callback for notification of state changes in socket state ( stream engine, tcp and ipc transport only )

Add disconnect and unbind documentation

Fix #366 - On Windows, preventing sockets to be inherited by child processes.

Simplify encoder's loop

Fix issue #268

This patch fixes a bug in the message encoder which was
responsible for computing incorrect message offset.
The bug affected PGM receiver making it unable to
decode inital messages.

Fix for issue 355 and fix for compile error with Visual C++ 2008

File decoder.cpp does not compile with Visual C++ 2008:

1>c:\tmp\libzmq\src\decoder.cpp(117) : warning C4003: not enough actual parameters for macro 'max'
1>c:\tmp\libzmq\src\decoder.cpp(117) : error C2589: '(' : illegal token on right side of '::'
1>c:\tmp\libzmq\src\decoder.cpp(117) : error C2059: syntax error : '::'
1>c:\tmp\libzmq\src\decoder.cpp(117) : error C2143: syntax error : missing ';' before '{'

This error is caused by the precense of a macro 'max' when including
'windows.h'. To solve this problem, the preprocessor macro /DNOMINMAX must
be specified.

Fix for issue 355. Added missing source files dealer.cpp, device,cpp and router.cpp. Removed source files no longer present: xrep.cpp and xreq.cpp