message: Add set method to Structure
diff: @@ -159,6 +159,8 @@ protected:
  void turnsToBuild(int newTurnsToBuild) { mTurnsToBuild = newTurnsToBuild; }
  void maxAge(int newMaxAge) { mMaxAge = newMaxAge; }
  + void integrityDecayRate(int decayRate) { mIntegrityDecayRate = decayRate; }
  +
  void repairable(bool isRepairable) { mRepairable = isRepairable; }
  virtual void defineResourceInput() {}
  