First working version

All tests pass on Cygwin and on Windows (when run from cmd).

Exception: support for UTF-8 filenames is not yet implemented.

NOTE: The attached file is an archive of Cream's gvim-8-0-1553.exe from SF. I had to copy in libwinpthread-1.dll from Cygwin x64 /usr/x86_64-w64-mingw32/sys-root/mingw/bin to get it to run. I am putting it here so Appveyor can grab it.

NOTE 2: Appveyor YML reference