RC_Channel: added percent_input() function

useful for plane flaps
Plane: use percent_input() for flaps
Plane: removed some unused functions
RC_Channel: added support for separate wheel steering channels on planes
Plane: added support for a separate steering channel

good for ground steering on larger aircraft
Rover: support k_steering channel
Copter: remove CLI tests for gps, logging, radio

Required to shrink the firmware down so that it can fit on the APM2
boards
Git: ignore xml files produced by Plane autotest
Copter: move report_compass out of the CLI

This function is also used by compassmot.  Having it strictly part of
the CLI causes a compile error when the CLI is disabled
Copter: disable the CLI by default

This is unfortunate but master's flash size is over the APM2 limit
Mount: add get_mode and set_mode_to_default methods
Copter: restore mount's mode to default after ROI completes
Notify: brighter RGB LED when on battery power
Replay: fixed for rover logs
Replay: fixed compass readings on rover
AP_Baro: fixed linux build of BMP085 driver
AP_NavEKF : Fix bug in initial East mag field state variance
Frame_Parameters: Added Skywalker
Frame_params: Updated 3DR Quad for Tarot Gimbal
Frame_params: Updated 3DR X8 for Tarot Gimbal