Port tests to windows and add to cmake build.
Fix up threading code from port tests to windows.
Merge branch 'master' of https://github.com/zeromq/libzmq
Fix running tests from cmake on linux.
Add #include to string.h in blob.hpp

Required for memmove(), memcpy()
Add try_lock() to mutex_t
Add scoped_lock_t syntactic sugar
Declare ZMQ_CONFLATE option
Implement double buffer for conflate option

Add simple double buffer implementation tailored to handle msg_t,
i.e invoke msg_t::close instead of destructor and so on.
Seems to me mutex is good enough at this point.
Plug in dbuffer to serve the ZMQ_CONFLATE option

ZMQ_CONFLATE option is passed to pipepair() which creates a usual
ypipe_t or ypipe_conflate_t and plugs it into pipe_t under a common
abstract base.
Update doc for ZMQ_CONFLATE socket option
Merge pull request #624 from ricnewton/master

Port tests to windows and add to cmake build.
Merge pull request #627 from ianbarber/master

Attempt to fix disconnect not respecting linger
Added message type for constant messages
Fix indentation
Merge pull request #630 from ulikoehler/cmsg

Optimized zmq::msg_t for constant messages
Minor fixes to doc ; added zmq_msg_init_data() assert preventing deferred segfault
Add test for ZMQ_CONFLATE option
Fix spaces before comments
Re-add comment line from cmsg branch