Splitted image pipeline for pointcloud streaming

Splitted image pipeline for pointcloud streaming

<!-- A turtlebot -->
https://github.com/turtlebot/turtlebot/blob/master/turtlebot_bringup/launch/3dsensor.launch


<!-- Remote Side -->
  <arg name="camera" default="camera"/>
  <arg name="depth" default="depth_registered"/>
  <arg name="points" default="remote_points"/>
  <arg name="nodelet_name" default="remote_nodelet"/>
  <arg name="respawn" default="false"/>
  <arg     if="$(arg respawn)" name="bond" value="" />
  <arg unless="$(arg respawn)" name="bond" value="--no-bond" />

  <node pkg="nodelet" type="nodelet" name="$(arg nodelet_name)"  args="manager"/>
  <group ns="$(arg camera)">
    <node pkg="nodelet" type="nodelet" name="remote_points_xyzrgb" args="load depth_image_proc/point_cloud_xyzrgb /$(arg nodelet_name) $(arg bond)
      <param name="image_transport" value="compressed"/>
      <param name="depth_image_transport" value="compressedDepth"/>
      <remap from="$(arg depth)/image_rect/compressedDepth" to="$(arg depth)/image_rect_raw/compressedDepth"/>
      <remap from="$(arg depth)/points" to="$(arg depth)/$(arg points)"/>
    </node>
  </group>
...