Make zctx_interrupted volatile

To be absolutely safe, in the presence of signals a flag variable
should use the volatile keyword. If the compiler was capable of
inter-library optimization, then it would be possible for it to
assume that since the interrupted flag is never changed by code
in the normal path that it was always true.
Merge pull request #33 from shemminger/master

small const changes
Merge pull request #39 from shemminger/volatile-zctx

Make zctx_interrupted volatile
Fixes problems compiling czmq with libzmq3.x on UNIX

- Added <sys/uio.h> as libzmq3.x requires this header
Add zsocket_disconnect binding

Current czmq lib is not offering the binding to the new disconnect
functionality. This patch makes disconnect available on czmq library.

If czmq is being bound to a version earlier than 3.3.0 disconnect
functionalities won't be available.
Merge pull request #42 from jlopex/master

Fixes issues #40 and #41
Change order of includes on czmq_prelude.h

Instead of adding zmq.h at the beginning do it at the end.
Do not show disconnect on old zmq versions

Add preprocesor check to detect libzmq version on zsocket.c
Merge pull request #45 from jlopex/master

Fixes issues #43 and #44
Fixed issue #48
Updated man pages
When arguments contain null bytes, strlen fails
Merge pull request #50 from raggi/master

Fix for vsnprintf usage to ensure all data is sent
Merge pull request #49 from hintjens/master

Fixed router_behavior and man pages
Fix #52
Merge pull request #54 from mkoppanen/fix-52

Fix #52
Code style fixes
Fix build error with SDK 7.0a and order of WinSock header.
Fix C++ incompatibilities with casting void.
Convert poll_size to size_t as more appropriate for usage.
Merge pull request #55 from steve-o/win64-fix

Fix build on Win64 and cleanup poll_size.
Fix 64-bit word dereferencing on 64-bit archs.