[Bug] No implementation of setDirOfAnisotropy(const NxVec3&a

The method setDirOfAnisotropy(const NxVec3&) in NxOgreMaterial.h don't have a implementation.

So I use setDirOfAnisotropy(const Ogre::Vector3 &vec) instead.

Not really a bug. But I will get around to implementing a NxVec3 and float3 alternatives for all of the classes.

It will be necessary when I move the Ogre RenderSystem to a separate project.