empty implementation for pure virtual methods

PlanningRequestAdapter::initialize() is now pure virtual so we have
to provide an empty implementation on each subclass.

See also moveit/moveit#1621

industrial_trajectory_filters/include/industrial_trajectory_filters/filter_base.h

@@ -172,6 +172,11 @@ template<typename T>
     }
     ; // original FilterBase method
 
+    /**
+     * Empty implementation of pure virtual function
+     */
+    virtual void initialize(const ros::NodeHandle& node_handle) override {}
+
   protected:
 
     /**

industrial_trajectory_filters/src/add_smoothing_filter.cpp

@@ -123,7 +123,12 @@ class AddSmoothingFilter : public planning_request_adapter::PlanningRequestAdapt
     }// end of if successful plan
     return result;
   };
-
+
+  /*!
+   * Empty implementation of pure virtual function
+   */
+  virtual void initialize(const ros::NodeHandle& node_handle) override {};
+
 
 private:
   ros::NodeHandle nh_;