#80 Enable compiling on windows without MinGW

[Jacob Minsky]

Only a few things are needed to enable compiling on Windows with Visual Studio without MinGW:

1. Include a version of dirent.h
2. change some syntax which is not supported by VS to simpler syntax
3. Some options

Compiling with Visual Studio makes it much easier to debug on Windows - using the regular VS debugger.

I have all the changes needed to enable this, but it would be somewhat inconvenient to post here as a diff. Maybe I can attach it as a file?