message: num motion primitives getter
diff: @@ -32,6 +32,7 @@ class BehaviorMotionPrimitives : public BehaviorModel {
  typedef unsigned int MotionIdx;
  MotionIdx AddMotionPrimitive(const Input& dynamic_input);
  + MotionIdx GetNumMotionPrimitives() const {return motion_primitives_.size();}
  void ActionToBehavior(const MotionIdx& motion_idx);
  virtual BehaviorModel *Clone() const;
  