WinRT native C++ support allowing building of static libraries

New ENABLE_WINRT_MODE_NATIVE=ON for native C++ and now can set BUILD_SHARED_LIBS=OFF and BUILD_WITH_STATIC_CRT=OFF (or leave it ON which results in even larger large lib files which are generally not needed as the CRT is distributed with all WinRT platforms) to build statically linkable WinRT libraries which cannot be done with C++/CX.  For many developers who will only use pieces of the library, this should dramatically cut down on code size and complexity as will have less files.  Note I am not talking about statically linking the VC runtime.  The primary difference I see between C++ and C++/CX is in static linkage to the library being built and not its dependent libraries which will still be the DLL versions.