AltitudeHold: tune the amount of tilt compensation

The existing code would still drop during forward flight,
because of the non-linearities of open loop ESCs. This
allows tuning the amount of tilt compensation.
AltitudeHold: make compensation amount a uint16

Being able to only go to the power 2.5 was insufficient to
maintain forward flight at steeper angles.
Updated tools.mk for compatibility with Mac OS 10.10
updated qt for all platforms
FlyingF4: Allow telemetry by default
Merge pull request #1219 from larsjohnsen/flyingf4_telemetry_fix

FlyingF4: Allow telemetry by default
osd: correct heading value for navi waypoint
Merge branch 'draco' into draco_experimental
Merge pull request #1216 from henkf/yosemite

Updated tools.mk for compatibility with Mac OS 10.10
Merge pull request #1171 from peabody124/tune_tilt_comp

AltitudeHold: tune the amount of tilt compensation
Merge pull request #1204 from strnadda/frskysport

FrSKY SmartPort UAVO bridge
Merge remote-tracking branch 'upstream/next' into draco
VtolPathFollower: makes RTH altitude and RTH velocity adjustable in settings
VtolPathFollower: emergency land when gps data unuseable for navigation

Gives some predictable behavior to VTOL path follower in case of
GPS signal lost (or unusable quality). When GPS lost, it will wait
and continue operations for 2 seconds to ignore short-term GPS glitches
and then emergency landing is enabled. In emergency landing VTOL attitude
is stabilized to be level and throttle is controlled to achieve
configured landing  vertical speed.
failsafe: make failsafe behavior configurable
failsafe: failsafe_control can now switch to RTH flight mode

If configured, Return To Home flight mode is selected when RC transmitter
signal is lost. There is protection against accidental RTH activation
when last known throttle input was 0. It also do some configuration
and alarms sanity checks before activation and when it failed, old-style
"throttle cut" failsafe kicks in.

GPS signal quality is evaluated by VtolPathFollower itself and in case
of low-quality or no signal, it renounce horizontal control, set level attitude
and start descent immediately at configured landingRate velocity.
failsafe: fixed uninitialized variable
failsafe: updated warning message
Merge branch 'failsafe' into draco_experimental
Merge branch 'draco' into draco_experimental