Handle empty RIG definition

[DM5EA]

If the RIG definition in the config file is empty ignore it and just connect the KPA500. Handle this as a special option of the TRXhamlib object. Allow to make a connection with setting a flag noTRXconnected. Use this flag inside the class in all functions. Those the other parts can use an instance of this class, but the methods will return nothing. Check, if this causes any problems.

The purpose is to make just a simple remote control of the KPA500 without interaction towards the TRX.