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 #246 from ulikoehler/zmutex_try_lock

Add zmutex_try_lock
Merge pull request #251 from hintjens/master

Various cleanups to zctx
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