- curve geometry curve panel wasnt displaying with no active spline

- graph export didnt work for constraints with no subtarget
- utility functions for duplicating a set of bones and blending between 2 sets

release/scripts/ui/properties_data_curve.py

@@ -133,8 +133,7 @@ class DATA_PT_geometry_curve(DataButtonsPanel):
         if obj and obj.type == 'SURFACE':
             return False
 
-        curve = context.curve
-        return (curve and curve.active_spline)
+        return context.curve
 
     def draw(self, context):
         layout = self.layout