Copter: rename failsafe to failsafe_radio

Makes way for separation of failsafes for throttle, gps and gcs
Copter: GPS Failsafe implemented

Switches to LAND mode 5 seconds after losing GPS if you're in a flight
mode that requires a GPS
Rover: fixed PX4 MPU6000 driver for rover
HAL_PX4: auto-create APM directory on SD card
InertialNav: remove 3sec limit on position est after losing GPS
Copter: bug fix for auto missions over 320m

get_throttle_althold_with_slew's target_alt parameter defined as int16_t
(instead of int32_t) meaning missions with altitudes >320m could wrap
around and become negative.
Copter: leonard's smoother alt-hold transition

Target altitude when entering alt-hold is based on a projection from
current alt and climb rate
GPS_UBLOX: fixed auto-config of baudrate

this fixes the setting of the baudrate on a uBlox that is configured
for 9600. It fixes the NMEA message to have a \r\n, plus sends the
NAV_SOL rate config before the NMEA baudrate config message.

This fixes issue #159
Copter: fix init of wp_verify_byte so wp alt is always required
Copter: remove unused crosstrack variables and parameters

Cross track is still calculated internally to the wpnav controller so we
should move this to a library and still report it to the ground station
Copter: remove tilt compensation parameter

Note: this idea of feed forward tilt compensation is being incorporated
into the inertial nav based loiter and wp controllers but does not
require a separate tunable parameter
Copter: remove #define for CROSSTRACK_GAIN

Note: the cross track is still calculated inside the inertial nav based
loiter and wp controls but it's no longer requires a tunable parameter
HAL_PX4: workaround problem with APM file on SD card

this works around file redirection bug from earlier firmwares
HAL_AVR: fixed build.Examples in autotest
build: added all 7 copter frame types to binary build
Tools: added the top level scripts for autotest
Tools: build all the PX4 copter frame types
Copter: fix to allow building HIL_MODE_SENSORS
Copter: remove support for CLI Slider
Copter: remove unused function