Removed PRINTF validation from man pages

- was mucking up man page contents
- moved to end of header file, outside API section
- simplified macros in czmq_prelude.h
Added sys_daemonize() method
Added zchunk_consume / exhausted

This allows an application to merge chunks together in an efficient
manner, without copying.
Added selftest for zchunk_exhausted
Merge pull request #420 from evoskuil/master

Update VS 2013 projects, remove hardwired libzmq ref and default to NuGet.
Merge pull request #418 from hintjens/master

Added zsys_daemonize method
Ensure gcc defines uint
Merge pull request #422 from hintjens/master

Ensure gcc defines uint
Ensure gcc defines uint -- fixed
Merge pull request #423 from hintjens/master

Ensure gcc defines uint -- fixed
rolled back the other changes and retained only the nuget configuration.
Merge pull request #424 from phreed/master

Added the nuget configuration.
Generated documentation
Updated man page for zchunk
Generated documentation
Added zlog system logging facility

- on UNIX/LINUX, uses syslog
- on other systems, does an fprintf() to stderr, for now
Merge pull request #426 from hintjens/master

Added zlog syslog class, and other smaller fixes
Added missing prototypes for zlog class
Added further prototype to zlog
Add project files for VS2010