* Will allow to load data if DB is not accessible / available
* Also allows to save, so a special set can be saved for testing/forensic.
* fixed status bar, as received data no longer means DB is alive
* renamed to connectDataReadSignal
* removed unused individual signals, e.g. vatsimMetarsRead -> replace by data read signal + entity flag
* added data in METAR class (kept there, not in airspace monitor) -> reader aware
