CommonProbeDisplay -- A protocol underlying ProbeDisplay and CompleteProbeDisplay
This protocol provides the common interface to all kinds of ProbeDisplays.
This method maintains consistency between the values of the probedObject's variables and the values which are displayed in the ProbeDisplay. Ideally, this method should be called every time the object is modified by the simulation. In practice, the user schedules an update on the probeDisplayManager which in turn communicates to all the active ProbeDisplays in the system.