Support for MS Visual C++

Hi there, once again requesting a tweak of the build and testing on Windows, this time for Microsoft Visual C++.

Naturally I tested this with MSWin32 Perl + MSVC++, but also verified that it sill worked with MSWin32 Perl + gcc and Linux Perl.

Happy to adjust the style if it isn't quite right, or run through the tests again if you want to tweak it yourself.

Cheers.