To simulate two robots

This is ticket #3.

1. The file that should be actually copied in order to create twoRobots.world is in directory .../stacks/simulator_stage/stage/world

2. The modification mentioned for the world file will work if you placed the copy (twoRobots.world) directly on the stage directory.

3. Here is a screenshot of the world as well as the two terminals with which we can teleoperate the two robots:



4. The nodes that are running and their topics are as follow:











If we look at the launch files we will see that in tworobots.launch the robot1 node is determined and is running the stageros node which determines that we are going to use the recently created twoRobots.world file. In each of the files we will find one node for teleoperation (Teleop_Base1 and Teleop_Base2) each of them with their particular publishing velocity topic.

Here we can see that each one of the robots is assigned an independent set of transformations.