syncing niflib with xml (note: Union field missing from BoundingVolume; see niflib hack in docsys/nifxml.py)

Add helper method to ControllerSequence which allows for adding item by name and not with target attached.

Update UpdateTangentSpace to match nifskope and add my algorithm adapted from the Obsidian developers version.

   - Fix issue with exporting Skin data causing missing vertexes in nifskope
   - add helper methods for collision related export.
   - fix crashes when exporting animation

Add helper methods to transform shape and fix some typos.

Add miscellaneous collision support helper methods

It seems that a NIF file with NULL property links is still able to be opened by the game engine, so added tests for this in a few places rather than assuming that all links are not NULL.

Added more NormalizeKeys functions.
Added some other functions to some controllers to expose their data.

Separated reference counting features of NiObject into new RefObject class.  This way they won't be buried in the obj folder.
Started adding NormalizeKeys functions to data objects, interpolators, and controllers that deal with keys.  Not yet finished.

Fixing paths in MatTexCollection.cpp to be relative.