UV Editor: Remove Unimplemented Show Edges Option

Show Edges option in the UV editor does not do anything. Only RNA/DNA
code could be found, so it is save to be removed.

Differential Revision: https://developer.blender.org/D5446

release/scripts/startup/bl_ui/space_image.py

@@ -961,7 +961,6 @@ class IMAGE_PT_view_display_uv_edit_overlays(Panel):
         col = layout.column()
 
         col.prop(uvedit, "edge_display_type", text="Display As")
-        col.prop(uvedit, "show_edges", text="Edges")
         col.prop(uvedit, "show_faces", text="Faces")
 
         col = layout.column()