autoconnect aseba switch

Aseba Switch can discover targets using zeroconf. In a classroom situation, it might be inconvenient for the teacher to specify each target when starting the switch. I propose an option --autoconnect name that tells Aseba Switch to automatically connect every target matching name that it discovers.

Typically this would be --autoconnect Thymio or perhaps --autoconnect Dummy.

This might also be useful in the simulator, so that targets could be added to the playground without the need to change the specification of the Aseba Switch process.

(A future refinement could be to add a --blacklist target option to exclude a specific target.)