Sprayer: fixed example sketch
GPS: add GPS_UBLOX_passthrough sketch

This sketch allows the user to configure the Ublox GPS using U-Center
without the need for an FTDI cable.
GPSGlitch: update @Range for RADIUS and ACCEL params
Rover: fixed throttle control in reverse

throttle nudge was being miscalculated
Rover: added support for uartD
Rover: fixed VFR_HUD.throttle for reverse
Copter: update @Range for Rate PIDs and Sonar

This will reduce false positives in DroneShare's tlog analyser
Copter: shorten g.arming_check_enabled variable

g.arming_check_enabled shortened to g.arming_check
DataFlash: fixed SITL dataflash logging

block numbers are 1 based
DataFlash: added RCIN and SRVO log methods
Plane: added RCIN and SRVO logging
Rover: changed SERIAL3_BAUD to SERIAL1_BAUD

and add SERIAL2_BAUD for systems that have it
Plane: added SERIAL2_BAUD and rename SERIAL3_BAUD to SERIAL1_BAUD
AP_HAL: added get_system_id() method on Util
HAL_PX4: support get_system_id() on PX4
Plane: use log system ID if available
Rover: log system ID if available
Copter: log system ID if available
Copter: added uartD support

this also brings GCS_Mavlink.pde closer to the plane implementation
Copter: removed extra features of copter telemetry merge