adding a basic check for windows absolute paths

I see what you mean about ATS getting confused by the path name, but I don't quite follow the [symlink suggestion](https://groups.google.com/d/msg/ats-lang-users/BoEWYOCGR9E/QRPxzMdbKk8J).

This is an apparent fix; I tested it and the error is no longer there, but please check the logic in case I missed something.

It is less of a dirty hack, but still a dirty hack - but that is the situation we are in if we want to use a Cygwin program from outside of Cygwin.