Reason was: hardcoded channel spacing to 8.33kHz
As a result changed to channel spacing based on COM unit, which could also be changed at runtime
* the issue itself was in own aircraft context
* added functions for channel spacing
* changed to COM unit channel spacing (instead of hardcoded spacing)
- nthIndexOf
- measurement unit can be parsed case insensitive
- CSimpleCommandParser::remainingStringAfter from n-th space
- improved frequency parsing
* avoid virtual functions in modulator related classes
* removed unused isDefaultValue()
* using null values (which was not present when class was written)
* removed destructor