- Includes WindowsUnicodeToolShim.h.
- Replaces sprintf_s() with std::ostringstream.
- Replaces fopen_s() with fopen_utf8().
- Switches to the toolMain() wrapper, which is a no-op on except on
Windows, where it should improve Unicode support, though I can't test
that on my end.
- Replaces \ with / in paths, which should still be Windows-compatible.