#104 Support of idx/sub created by BDSup2Sub

[Spyros K]

I don't really know what is the difference between DVD idx/sub subtitles and the idx/sub ones created by BDSup2Sub utility, but the 2nd format is not rendered at all.
It would be nice if you added support of those since this BDSup2Sub.jar utility is necessary to build 3D subtitles.