Add further opus info fields.

More information about Opus streams implemented. I know it's quite a lot of changes, but hopefully you can review it and incorporate them into VorbisJava. Comments, hints, bug reports welcome!

I pretty much did what info_opus.c in the opus-tools-0.1.9 does. Multiple opus streams are not supported right now.

I changed OggFile/OggPacketReader so it can be reset to the position before the info extraction. OpusInfo needs to read the entire stream for its work.

The frame check is removed in this pull request.