6.13 gps

The `gps` interface provides access to an absolute position system, such
as GPS.

**struct player_gps_data** :
The `gps` interface gives current global position and heading information;
the format is:

**uint32_t time_sec;****uint32_t time_usec;**GPS (UTC) time, in seconds and microseconds since the epoch.

**int32_t latitude;**Latitude, in 1/60 of an arc-second (i.e., 1/216000 of a degree). Positive is north of equator, negative is south of equator.

**int32_t longitude;**Longitude, in 1/60 of an arc-second (i.e., 1/216000 of a degree). Positive is east of prime meridian, negative is west of prime meridian.

**int32_t altitude;**Altitude, in millimeters. Positive is above reference (e.g., sea-level), and negative is below.

**int32_t utm_e, utm_n;**UTM WGS84 coordinates, easting and northing (cm).

**uint8_t quality;**Quality of fix 0 = invalid, 1 = GPS fix, 2 = DGPS fix

**uint8_t num_sats;**Number of satellites in view.

**uint16_t hdop;**Horizontal dilution of position (HDOP), times 10

**uint32_t err_horz;**Horizonal error (mm)

**uint32_t err_vert;**Vertical error (mm)