wrist_cal_node does not exit cleanly

[DavidMerzJr]

If CTRL+C is used to terminate a launch file that contains wrist_cal_node, the node refuses to die unless roslaunch escalates to SIGTERM. This is quite bothersome when testing some functionality and frequently starting/stopping a launch file.

Below is an example launch file that exhibits this behavior when run (and terminated).

<launch>
  <!-- The node that collects images and runs a wrist calibration optimization -->
  <!-- In this case, robot_support is the name of the package containing this file -->
  <node name="wrist_cal_node" pkg="industrial_extrinsic_cal" type="wrist_cal_srv" output="screen" respawn="true">
    <param name="yaml_file_path" value="$(find robot_support)/yaml/"/>
    <param name="camera_file" value="astra_camera.yaml"/>
    <param name="target_file" value="calibration_target.yaml"/>
    <param name="target_mount_frame" value="base_link"/>
    <param name="camera_mount_frame" value="tool0"/>
    <param name="save_data" value="true"/>
    <param name="data_directory" value="$(find robot_support)/data/"/>
    <param name="use_circle_detector" value="true"/>
  </node>
</launch>