Fixes for Windows (MSVC and MinGW), some tweaks

Some tweaks, warning fixes, and header fixes for tuxeip and readtag on Windows using MinGW. ```unistd.h``` is needed for close() under non-Windows platforms, otherwise ```io.h``` is needed. WSAStartup and WSACleanup calls are needed to use sockets under Windows. For more detail see each commit. Thanks for this code!