Added support for 3Delight path tokens for image and NSI filenames.
Now we can combine Houdini vars such as $HIP, $HIPNAME etc, with 3Delight tokens such as , etc. Only the ones that can be used on image and NSI output paths are supported. E.g you can't add <shape_name> which is a valid token of 3Delight and expect it to be expanded. This commit closes #490 (closed)