Copter: update AC3.1-rc2 release notes for COMPASS_ORIENT change
Iris Params: set COMPASS_ORIENT to 0
Iris Params: update volt divider for 4-in-1 ESC
AP_HAL: added hal.gpio->usb_connected() function

this replaces the USB_MUX_PIN on APM2, and works on PX4 and FMUv2
Plane: use new usb_connected() function
Copter: use new usb_connected() HAL function
Rover: use new HAL usb_connected() function
AP_HAL: convert to unix file format
AP_Math: fixed DOS CR/LF errors
GCS_MAVLink: remove CR/LF
AP_Notify: convert to unix style file
AP_InertialSensor: removed the flash_leds() callback

AP_Notify now handles this
libraries: fixed examples for no flash_leds() callback
Rover: removed flash_leds() calls
Copter: removed flash_leds() calls
Plane: removed flash_leds() calls
VARTest: removed old pin defines
Plane: disable battery failsafe when usb connected
gitignore: ignore Build.ArduPlane
AP_InertialSensor: fixed another example build