message: In class TMOP_integrator, add method that can be used to update the
  "original" nodes, used when limiting is enabled.
diff: @@ -576,6 +576,9 @@ public:
  nodes0 = &n0;
  }
  + /// Update the original/reference nodes used for limiting.
  + void SetLimitingNodes(const GridFunction &n0) { nodes0 = &n0; }
  +
  /// Sets a scaling Coefficient for the quality metric term of the integrator.
  /** Note that the Coefficient is evaluated in the physical configuration and
  not in the target configuration which may be undefined. */
  