DataFlash: added baro dataflash logging
AP_Airspeed: expose get_temperature()
Plane: added baro and airspeed logging

including raw temperature and pressure values
Plane: prepare 2.78beta2
Plane: added RSSI_RANGE parameter
AP_Airspeed: fixed example build
AP_InertialSensor: fixed example builds
AP_Math: fixed example build
AP_Notify: fixed example build
Plane: prepare for 2.78 release
Copter: firmware to AC3.1.2-rc1
Copter: remove unused compat.pde entries
Plane: fixed RSSI_RANGE enum

many thanks to Valince for spotting this
Plane: prepare for 2.78b release
AP_Param: expose check_var_info() as a public symbol
Plane: check the parameter table on startup
Copter: check param table on startup
Rover: check param table on startup
3DR_Y6B_RTF: added to standard frames
3DR_Y6B_RTF: Updated for FlySky TX