Client may send InvoiceRecipientPersonId even the FlightCostBalanceType is set other

[pschuler78]

The client may send a Guid für InvoiceRecipientPersonId, but the FlightCostBalanceType is not 5 (invoice to person). In this case, the server should ignore the property InvoiceRecipientPersonId and should not add the FlightCrew with the InvoiceRecipientPersonId, but due to a bug, the server creates the additional record.

The client send the Guid on the property InvoiceRecipientPersonId only if already a flight with FlightCostBalanceType = 5 was created before in the same session. All following flights will have the same Guid on the property InvoiceRecipientPersonId.

This means, that the client does not check the FlightCostBalanceType settings.

See also flightlog/flsserver#76