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