activityTime

Could be overridden to supply different approach for determining the activity delay. The current approach does the following.

1. Checks the useQObjectForActivityTime option and if true uses the qObject's valueObject to determine the activity time. If this option is used, an illegal state exception will occur if the qObject's valueObject property has not been set.

2. Checks if the activityTime property has been set and if so uses the supplied StationActivityTimeIfc to determine the activity time.

3. If neither the first two options are used, then the activity time will be determined by the supplied RVariableIfc, which is zero by default.

If set and the station does not use the qObject for determining the activity time, then the supplied function will be used.