Docker build files and scripts for running ros2 galactic

If you want to modify the images please refer to "building" below. If you are satisfied with using the pre-built images you need to:

• Make sure you have installed nvidia-docker. Follow the instructions. Note that the images should work with vanilla docker as well, but will not benefit from hardware acceleration which may be prohibitatively slow.
• Modify the script in start_interactive.sh. Substuitute the line that mounts the second volume and change the path /home/tsv/code/ros2ws to point ot a folder where you have your ROS2 Workspace.
• Run the script to start up a container.
• If you want to have an additional terminal in the container, run the script connect_running.sh. Pay attention that the new terminal needs to run "source /ros_entrypoint.sh" in order to see the ROS2 installation.

The steps above should work by pulling the docker image from th associated docker hub repository. If, for some reason, you want to build your own images and modify something then:

• Modify the contents of the Dockerfile as you see fit.
• Edit build.sh and tag the image with your own unique name
• Run build.sh. Subsequently modify the start_interactive and connect_running scripts to use your local image.