RuledSurface fixes, Switch Part_Mirror to SVG icon

RuledSurface fixes,
  claim children
  correct tool tip
  change default name from "Filled_shape" to "Ruled Surface"

Part_Mirror
  Switched icon in the tool bar, menu, and tree from
  the existing PNG icon to the also existing SVG icon

src/Mod/Part/App/PartFeatures.cpp

@@ -118,7 +118,7 @@ App::DocumentObjectExecReturn *RuledSurface::execute(void)
             this->Shape.setValue(shell);
         }
         else {
-            return new App::DocumentObjectExecReturn("Curves must either be edges or wires.");
+            return new App::DocumentObjectExecReturn("Curves must either be both edges or both wires.");
         }
         return App::DocumentObject::StdReturn;
     }