Win32 + Win64 (WIP)

* improved main cmake lists file and keccak cmake lists file
* changed cmake minimum version to 2.8 as 3.0 isn't required
* defined restrict on VC++ to be __restrict
* added export keyword to public interface functions (windows only)
* the library now compiles with visual c++ and mingw (tested with visual studio 2012)
* changed memset_s to be memset on WIN32
* don't inline on visual c++
* changed lot of code to be less c99 so that the c compiler part of visual c++ can compile it
* disabled VC++ warning 4244
* vc++: removed what appears to be unused headers (stdalign.h, stdbool.h)
* using __inline on VC++ (static inline fails)
* added header location as interface directory (nice for dependent libraries using cmake)
* defined NO_LIBUTIL in cmake instead of config.h