Finished basic version support � still need to implement new block reading scheme for version 5 and up.
Updated all basic blocks with correctly versioned attributes from DocSys database.
Updated all data blocks except for NiSkinPartition and NiControllerSequence to react correctly to known version differences up to 10.1.0.0.
All blocks but the above now have both a Read and a Write function.

Added NiParticleSystemController block and started on particlegroup attribute.
Changed the type name of some attributes to match DocSys database.
Changed IndexAttr to LinkAttr for consistency.  Type name is now "link."
Fixed inheritance of light blocks � didn�t notice they didn�t work since no official file seems to use them.

Added Matrix22 and Float2 types.
Changed bump mapping members  in Texture struct to use Matrix22.
Changed members in BoundingBox struct to use Vector3 and Matrix33 types.

Un-commented attr_ref operator=(blk_ref) function.

Added a Set(float, float, float) function to the Float3 struct to allow setting all values in one call.

Changed Float3, Matrix33, and Matrix44 from C arrays to structures that mimic C arrays ensure accessibility from scripting languages.

Added template directives for new key templates to pyniflib.i.

Fixed a bug that was causing multiple copies of the same block to be written by WriteNifTree()

Added Write() Function for NiKeyFrameData, NiTextKeyExtraData, and NiStringExtraData
Added AExtraData class with a proper index attribute.  ExtraData blocks will now be part of the tree as they should have been.

Automated NiSkinInstance Skeleton Root attribute and AController Target Node attribute.  All back references should now be automatic.

Added a readout of a list of skin data blocks that are connected to each NiNode for testing.

Made NiSkinData and the bone nodes it references aware of each other so they can be properly destroyed.

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