Add nmea passthrough so you can use marauder as a gps device.

[aubreyshomo]

Added capability for the marauder to be put in NMEA passthrough mode via the "nmea" command. This relays NMEA sentences until the marauder gets a stopscan command. All other commands ignored and not echoed. stopscan not echoed but acknowledged.

Added two gps -g flag options: -g accuracy which prodives hdop, and -g nmea which provides the two standard NMEA sentences that relate the current position state in marauder. (Also, adds -g nmea -r for the most recent NMEA sentence received from the GPS, and -g nmea [-r] -p for the most recent NMEA sentence that is not one of the two locally generated that you get with just plain -g nmea. These two debug flags are not in help.)

Added a gps -n option, which can be gps -n all (for multisatalite mode), gps -n gps (spoof gps), gps -n glonass (spoof glonass), gps -n galileo (spoof galileo). defaults to all. not present in help. for compatibility with something that expects a specific sat type. (due to hacky workaround for "gps -g nmea" packets and MicroNMEA lib limitations.)

Tested with sd/gps daughterboard made by justcallmekoko and the following: flipper NMEA GPS from the app store, google earth, visual gps view, and gpscomplete (using gpsdirect driver) as a location sensor for windows.

You can turn your marauder into a gps device at 115200 baud outputting at 1hz, ignoring nmea commands, but providing nmea stream output for any flipper app you want, if you use the wifi dev board flipper version, or even using the uart to usb bridge, for anything that expects a normal nmea gps device on a desktop/laptop computer or navigation equipment.

With your wardriving kit, you also have a GPS device, and can use it as one.

nmea to start. stopscan to stop.

[aubreyshomo]

Changed my nmea scan code to 40, because you were using 39 for something new in your fork. It still shows a conflict I can't resolve, but I committed a flx for the actual conflict already.