Add logNMEA and an example

src/SparkFun_u-blox_GNSS_Arduino_Library.h

@@ -928,6 +928,9 @@ public:
 	void flushHNRPVT(); //Mark all the data as read/stale
 	void logHNRPVT(boolean enabled = true); // Log data to file buffer
 
+	// Helper function for NMEA logging
+	void logNMEA(boolean enabled = true); // Log NMEA data to file buffer
+
 	// Helper functions for CFG RATE
 
 	boolean setNavigationFrequency(uint8_t navFreq, uint16_t maxWait = defaultMaxWait);	//Set the number of nav solutions sent per second
@@ -1183,6 +1186,8 @@ private:
 
 	boolean ubx7FcheckDisabled = false; // Flag to indicate if the "7F" check should be ignored in checkUbloxI2C
 
+	boolean _logNMEA = false; // Flag to indicate if NMEA data should be added to the file buffer
+
 	//The packet buffers
 	//These are pointed at from within the ubxPacket
 	uint8_t payloadAck[2];				  // Holds the requested ACK/NACK