Created a new ComplexShape class which can currently be used to automatically...

Created a new ComplexShape class which can currently be used to automatically split the sort of complicated mesh that contains per-point-per-face attributes into NiTriShape classes.  Should support skinning as well, but has not been tested.
Added TexCoord == operator.
Changed type of Triangle members to unsigned short.
Color4 now defaults to all zeros.
NiAVObject::AddProperty now takes a const argument.
Fixed exception in NiTexturingProperty to throw a runtime_error instead of a string.
NiTriBasedGeom::BindSkin should now automatically finds the skeleton root by itself.  The skeleton_root argument has been removed.