Voltage probes allowed in multiwires, but voltage of outermost conductor depends on problem type

[Alberto-o]

Voltage probes are a recurring problem. In the full-wave solver they have been substituted by "line integral" probes, which reflect more accurately the operation that was being stored as voltage. In transmission line problems voltage has a more clear meaning, as long as we have a reference conductor. Hence, voltage probes will be allowed when using shielded and unshielded multiwires, with the following rules:

• In a full-wave problem, a voltage probe on a bundle returns the voltage of each conductor referred to its reference conductor (the shield surrounding it). For the outermost conductor, no voltage is returned, since there is not a clear reference.
• In a transmission line standalone problem there is a reference conductor or ground material. In this case the voltage of the outer conductor referred to that reference/ground is also given

Voltage probes are already implemented but the distinction above has to be made.