Fix: Import bhkLimitedHingeConstraint

Had no attribute sub_constraint, causing import to fail due to apply_scale() being called on it.

pyffi/formats/nif/__init__.py

@@ -2335,17 +2335,17 @@ class bhkLimitedHingeConstraint:
         def apply_scale(self, scale):
             """Scale data."""
             # apply scale on transform
-            self.sub_constraint.limited_hinge.pivot_a.x *= scale
-            self.sub_constraint.limited_hinge.pivot_a.y *= scale
-            self.sub_constraint.limited_hinge.pivot_a.z *= scale
-            self.sub_constraint.limited_hinge.pivot_b.x *= scale
-            self.sub_constraint.limited_hinge.pivot_b.y *= scale
-            self.sub_constraint.limited_hinge.pivot_b.z *= scale
+            self.limited_hinge.pivot_a.x *= scale
+            self.limited_hinge.pivot_a.y *= scale
+            self.limited_hinge.pivot_a.z *= scale
+            self.limited_hinge.pivot_b.x *= scale
+            self.limited_hinge.pivot_b.y *= scale
+            self.limited_hinge.pivot_b.z *= scale
 
         def update_a_b(self, parent):
             """Update the B data from the A data. The parent argument is simply a
             common parent to the entities."""
-            self.sub_constraint.limited_hinge.update_a_b(self.get_transform_a_b(parent))
+            self.limited_hinge.update_a_b(self.get_transform_a_b(parent))
 
     class bhkListShape:
         def get_mass_center_inertia(self, density = 1, solid = True):