added GUI elements for apriltag fence option
added GUI elements for apriltag fence option

Added an additional set of radio buttons in order to toggle which
kind of barrier is used in a simulated arena.

Note that these radio buttons are disabled when using an unbounded
arena since no boundaries are used.

BCLab-UNM/SwarmBaseCode-ROS,BCLab-UNM/SwarmBaseCode-ROS,BCLab-UNM/SwarmBaseCode-ROS,BCLab-UNM/SwarmBaseCode-ROS,BCLab-UNM/SwarmBaseCode-ROS,BCLab-UNM/SwarmBaseCode-ROS