[boost] [nowide] Switching to C++11 after 1.73 release

Hi, as Boost.Nowide is now release ready and will be included in the 1.73 release I wanted to announce that I'm planning to require C++11 for anything after. There are a few minor things which need different other libs of Boost for C++98 support and given the age of C++11 support in especially MS compilers I want to reduce the dependencies to (almost) nothing. I say "MS compilers" because this is a Windows-centric lib and will most likely most often be used with MSVC. However I'll evaluate supporting even some older MSVC versions making some C++11 features optional if possible. Best Regards, Alexander Grund