Support cross-drive linking #21
Description
Currently we cannot link a file to a different drive. E.g. cmdShim('C:\\a.js', 'D:\\a', () => {}) would generate files containg "$basedir/C:/a.js" or "%~dp0\C:\a.js", which are broken due to the unresolvable paths.
In this case, we can use an absolute path instead, i.e. using "C:/a.js" rather than "$basedir/C:/a.js".
If this is a valid use case, I'd like to work on it.