Consistent robot initialization in examples

[fmauch]

In our examples we use different approaches to initialize the robot. In the full_driver example, tool contact example and spline example we switch the robot off and on which is rather weird if you test it with a real robot. I think we could improve this and make sure it is consistent over all examples.

We currently do have a lot of boilerplate code copied between each example (such as parsing the IP address, initializing the robot, ...). This could be merged into one common header file, but that would also break that the examples are single-file only. I think, it might be worth doing this, though.