/// <summary> 
 /// Adds a new Color var to the supplied blackboard.
 /// Automatically handles undo.
 /// <param name="blackboard">The blackboard to add a new ColorVar.</param>
 /// <returns>The new variable.</returns>
 /// </summary>
 public static ColorVar AddColorVar (InternalBlackboard blackboard) {
     BlackboardUtility.RegisterVariableUndo(blackboard, "Add Color Variable"); 
     var newVariable = blackboard.AddColorVar(); 
     EditorUtility.SetDirty(blackboard);
     return newVariable;
 }