DataFlash: Log vDOP with GPS messages.

Due to the description string getting to long HDop was renamed as EPH with VDop as EPV (Which is the same terimnology  used to describe the MAVLink side). Status was shortened to stat as well.

libraries/DataFlash/DataFlash.h

@@ -211,6 +211,7 @@ struct PACKED log_GPS {
     uint16_t gps_week;
     uint8_t  num_sats;
     uint16_t hdop;
+    uint16_t vdop;
     int32_t  latitude;
     int32_t  longitude;
     int32_t  rel_altitude;
@@ -688,7 +689,7 @@ Format characters in the format string for binary log messages
     { LOG_PARAMETER_MSG, sizeof(log_Parameter), \
       "PARM", "QNf",        "TimeUS,Name,Value" },    \
     { LOG_GPS_MSG, sizeof(log_GPS), \
-      "GPS",  "QBIHBcLLeeEefB", "TimeUS,Status,GMS,GWk,NSats,HDop,Lat,Lng,RAlt,Alt,Spd,GCrs,VZ,U" }, \
+      "GPS",  "QBIHBccLLeeEefB", "TimeUS,Stat,GMS,GWk,NSat,EPH,EPV,Lat,Lng,RAlt,Alt,Spd,GCrs,VZ,U" }, \
     { LOG_IMU_MSG, sizeof(log_IMU), \
       "IMU",  "QffffffIIfBB",     "TimeUS,GyrX,GyrY,GyrZ,AccX,AccY,AccZ,ErrG,ErrA,Temp,GyHlt,AcHlt" }, \
     { LOG_MESSAGE_MSG, sizeof(log_Message), \

libraries/DataFlash/LogFile.cpp

@@ -720,6 +720,7 @@ void DataFlash_Class::Log_Write_GPS(const AP_GPS &gps, uint8_t i, int32_t relati
         gps_week      : gps.time_week(i),
         num_sats      : gps.num_sats(i),
         hdop          : gps.get_hdop(i),
+        vdop          : gps.get_vdop(i),
         latitude      : loc.lat,
         longitude     : loc.lng,
         rel_altitude  : relative_alt,