obscure feature: Display Custom Bone Shape at another bones transform.

Brecht and I took a fair bit of convincing on this one however Cessen was jumping through hoops to do without this feature.
Having the shape being an external mesh deformed by its own armature, which were both hidden but in the same layer *(so the depgraph would update them).
Without this some of the bones in the rig also dont make much sense when animating with.

release/scripts/ui/properties_data_bone.py

@@ -223,8 +223,11 @@ class BONE_PT_display(BoneButtonsPanel):
 
             if wide_ui:
                 col = split.column()
+
             col.label(text="Custom Shape:")
             col.prop(pchan, "custom_shape", text="")
+            if pchan.custom_shape:
+                col.prop_object(pchan, "custom_shape_transform", ob.pose, "bones", text="")
 
 
 class BONE_PT_inverse_kinematics(BoneButtonsPanel):