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
Remove delay options

These were exposed to users, but have subsequently been removed as
sockopts. They are currently only being used by ZAP, so I've moved it to
a simpl function call (actually it's only used in one case even in that,
so there may be a further simplification possible there).
Fix indentation
Add test for ZMQ_CONFLATE option
Add the Socket Identity info to the ZAP Messages

This change adds the socket identity infomartion from the socket to the
zap frames.  In doing this the ZAP is able preform different operations
based on different sockets.  This is not compaitable with the current ZAP
RFC, but that can be updated.  As the ZAP rfc is currently draft for I
did not change the version number.

Tests also modified and passing.
Merge pull request #626 from dkrikun/master

Add ZMQ_CONFLATE socket option
Merge in master changes
fix type on HWM
Merge pull request #631 from jrossi/master

Add the Socket Identity info to the ZAP Messages
get to clean compile under vs2012

Added some missing (but existing in branch) files to libzmq11 project needed
to compile as static library by VS2012 (at least), and fixed some warnings.
One warning remains in raw_decoder.cpp, which I'm leaving for now because I'm
not sure how project owners would like to fix it.
Merge pull request #633 from eburkitt/vs2012-clean-compile

get to clean compile under vs2012
Fixed markup so documentation can be built.
Merge pull request #634 from guidog/master

Fixed markup so documentation can be built.
Fixed silly port number.