Fix WinRT MSMF support

Visual Studio 2013/2012 for all Windows 8.1 or 8 combinations are now supported. Concurrency selection integrated. Code corrected to use the task library. This is stable enough for a merge as it now properly structured. The major changes are finished here. If HAVE_CONCURRENCY is not defined then the offending Win32 code is removed but initialization will always yield failure as it relies on it so defining HAVE_WINRT and HAVE_MSMF without HAVE_CONCURRENCY is somewhat useless but the option is at least respected. Non-library implementation is possible and my custom native C++ WRL library also requires on structures from the non-task part of the concurrency library.