Implemented simplest v6 unpacking.

[GreenWizard2015]

You might be interested in viewing https://github.com/GreenWizard2015/disunity/commit/c5cae22f1a5343cf820542c5ede1a34c9bd6baae
I made many little changes, so I wont risk do pull request, but you can copy main code (in BundleReader mostly) of working with v6 bundles. Unfortunately, it's required xz lib now, because it support lzma streams without header (in v6 there is slightly different header, without uncompressedSize field).
I hope my code will help you.
Best regards, GW.

P. s. tested only on one unity3d file with next properties:
"compressed": true,
"streamVersion": 6,
"unityVersion": "5.x.x",
"unityRevision": "5.3.6f1",

[Mactastic1-5]

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