Add explicit casts for MSVC compilation
Add missing headers/implementations to msvc11 project
Zchunk - cast to byte* and remove aligned (need windows equivalent)
Prelude - define sleep as Sleep for MSVC
define S_IRUSR as _S_IREAD for MSVC

cannot pass zfile selftest after this change. no good, but it lets me
compile for now.
Implemented zmutex_try_lock
Merge pull request #249 from pijyoi/master

bugfixes to zctx.c
Various cleanups to zctx

* Asserts that zocket isn't null when destroying it; the tolerance for
  null sockets is a bogus workaround against corruption of zctx from
  unprotected use in multiple threads.

* Renamed 'main' to 'shadow' to make more explicit (negative property
  names are not good).

* Renamed 'socketsMutex' to 'mutex' since (a) camelCase breaks our style
  guidelines, and (b) we have one mutex to protect the object, there is
  no value in qualifying the name.

* Cleaned up constructors, the code was messy.

* All methods that modify or read zctx properties needed to be protected
  by the mutex, otherwise we'll get random outcomes.

* I still do not like the multithreaded zctx; it is incompatible with the
  current code in zthreads (e.g. we don't need shadow contexts) and is
  not sufficiently tested IMO. Also, I still don't see a valid use case
  for it.
Fixes for issue #224

* Not tested on Windows.
* Defines _CRT_SECURE_NO_DEPRECATE for all MSVC versions above 1500
* Previously was done only for version = 1500
* Usual warnings on new code (casts and signed comparisons), fixed.
Merge pull request #246 from ulikoehler/zmutex_try_lock

Add zmutex_try_lock
Merge pull request #251 from hintjens/master

Various cleanups to zctx
Fixed compilation for MSVC
Added platform.h and other fixes for MSVC
Added cast to keep MSVC happy
Merge from upstream
Merge from upstream
MSVC: ignore lib, opensdf, suo and sdf files
MSVC: compile as C++
Merge pull request #253 from momo-the-monster/master

MSVC Compilation additions
Merge pull request #252 from hintjens/master

Fixed compilation for MSVC