RangeFinder: reduce PulsedLight max distance

Reduced from 25m to 14m
Copter: Use AHRS heading in GLOBAL_POSITION_INT message

The definition of the heading field for GLOBAL_POSITION_INT is the
compass heading, and so it is used for Plane and Rover.  Copter
however uses the GPS course over ground in this field.

My personal beef with this is simply that the mapping display in
MAVProxy is wrong for Copter.  The question is: Do any GCS currently
rely on this field for GPS course rather than getting it from
GPS_RAW_INT as they should?
Copter: add Y6 with all top props CW

Set FRAME parameter to 10
Copter: pre arm mag offset limit to 600 for PX4
Copter: update THR_MAX @Range and comments
Copter: increasd default logging for PX4, Pixhawk
TradHeli: bug fix for main rotor ramp up

The main rotor ramp was being held back by the rotor speed estimate
instead of being allowed to jump up to the estimate if it's lower.

Also fixed some incorrect indentation
Copter: remove AN0~AN15 pin definitions
Camera: correct _trigger_type comment
Copter: log flight mode to dataflash on start-up
Copter: ignore yaw input during radio failsafe
web: added icon for SiK firmware
web: fixed icon
Copter: reduce autotune min rate P to 0.01 (was 0.02)
GPSGlitch: reduce radius to 2m
Copter: AC3.1-rc8 release notes
Copter: reduce autotune min rate D to 0.002