Add some new options to better auto-detect where the imported nif is coming from and default to correct application based on root paths.  Also add some assistance for locating skeleton.nif files if needed.

Add options to force nubs to point back to parent node at the expense of the rotation data.  It looks better. Need to alter the zAxis instead I think.

2. Fix bug with matrix inversion missing.  
3. Use Point3(0,0,0) instead of Point3()