AP_Frsky_Telem: added initial Frsky telemetry library

based on work from the PX4Firmware tree, this adds a library which can
create and send Frsky telemetry packets
Copter: Add SERIAL2_PROTOCOL for GCS and FRsky telemtry

this allows selection of protocol type on telem2. The default is
MAVLink, but can be selected as FrSky protocol
Plane: Add SERIAL2_PROTOCOL for GCS and FRSky telemtry

This allows selection of protocol type on telem2. The default is MAVLink, but can be selected as FrSky protocol
Rover: Add SERIAL2_PROTOCOL for GCS and FRSky telemtry

This allows selection of protocol type on telem2. The default is MAVLink, but can be selected as FrSky protocol
Frame_params: Added Iris with 3 Positon Mode Switch.param
Rover: rename Tele2Protocol to Serial2Protocol
Copter: rename TELEM2_PROTOCOL to SERIAL2_PROTOCOL

this matches SERIAL2_BAUD
Plane: rename enum for Telem2Protocol
Copter: use hal.rcout to send servo output to GCS
AP_InertialSensor: some more debug info for VibTest
Copter: rename control_modes.pde to switches.pde
Copter: Thr and Batt failsafe disarm when landed

When throttle/radio failsafe or battery failsafe are triggered, the
vehicle will disarm if it is landed even if the throttle is not at zero.
Auto mode will disarm if landed and mission has not started.  This
ensures that the vehicle does not disarm during a mission land command
that appears mid way through a mission.
AP_NavEKF : Modified compass fail logic

If the vehicle can fly without a compass (a fly forward vehicle)
then if the compass times out (large errors for more than 10 seconds,
then it will be declared permanently failed and will not be
used until the filter is reset
Copter: prevent false triggering of ekf_check
Copter: rename EKFCHECK_COMPASS to EKFCHECK_THRESH

Renamed because this threshold is now used for both compass and velocity
variance.
Also minor reorganisation of ekfcheck but no functional change.
Copter: auto-disarm in Drift, Sport, OF_Loiter
build: fixed dependency on frame type in make target
Mission: bug fix to condition-change-alt

Fix contributed by oniondream, thanks!
Copter: version and release notes for AC3.2-rc4
BaroGlitch: init members to resolve compiler warning