Based on patch from Daniel Aleksandersen <code@daniel.priv.no>
Expands GPS specific GGA test with tests for GGA messages from other
well-known Talker IDs in NMEA 4.1 including Galieo, BeiDou, GLONASS,
and GNSS (generic/mixed source mode).
GGA messages use the same format regardless of the Talker ID.

* Improves device and GNSS network support.
* Improves accuracy for users in Europe, Russia, China, and elsewhere.
* Resolves compatibility problem with GPS devices that only report in
  GNGGA and not GPGGA even in single-network mode.

Fixes:#60