Implements Issue #20

This implements Issue #20.

Note: There are a couple of side effects from this request.

First, the system directory separator is now used automatically, since all relative paths are generated, at runtime, by the Windows API, and not hardcoded.  This changes the form of the relative paths in two ways:

First, paths will often be prefixed with the current path specifier (".\foo\bar\some file.txt")
Second, folders will no longer have the trailing forward slash that was added manually (".\Foo" instead of "Foo/")

The tests were updated accordingly.

In practice, this should have no negative impact.  Any use of the file path as a path will still work properly, and Path.Combine and related BCL methods should all handle this perfectly.