Add support for visualizing ROS pointclouds in director

[manuelli]

@patmarion can you point me in the right direction here?

[patmarion]

director/master includes a top level catkin_ws folder. first build director as usual, then build the catkin_ws. the director superbuild does this automatically when you enable USE_ROS see:

https://github.com/RobotLocomotion/director/blob/master/distro/superbuild/cmake/externals.cmake#L13

and:

https://github.com/RobotLocomotion/director/blob/master/distro/superbuild/cmake/externals.cmake#L642

note in the above code, after building the catkin_ws, it "installs" it by copying the libddROSPlugin.so file. To learn more about the details, look at the source code of the c++ code that was compiled to make that plugin. To run the plugin, here is a simple python snippet that can be added to any existing director code:

https://github.com/RobotLocomotion/director/blob/master/catkin_ws/src/director_ros/src/pointcloud_subscriber.py

The plugin starts a ROS node and spins it on a separate thread. The thread receives pointcloud messages and converts them to vtkPolyData objects, then it notifies Python that a new object is available. The python main thread grabs the vtkPolyData from the c++ thread and takes ownership.

[patmarion]

Oops, in the above post, please ignore the pointcloud_subscriber.py file I linked to. That file is out of date and should be deleted. This is the more comprehensive example file:

https://github.com/RobotLocomotion/director/blob/master/src/python/tests/testRosPlugin.py