Copter: fixed parameter path

fixes build of parameters
Copter: support logging while disarmed
Copter: remove extra in_mavlink_delay from should_log function

Also return false when logging disabled
Copter: add NearlyAll-AC315 LOG_BITMASK description
Copter: remove LOG_FROM_STARTUP define

This compile-time method is obsolete now that we have the logging while
disarmed feature
Parachute: set servo or relay to off position on every update

This resolves the issue of the parachute servo's position not being
initialised to the off position due to an ordering problem of the
auxiliary servos being initialised after the parachute object.
Copter: log DCM reported roll-pitch and yaw error
AP_Motors: reduce slow-start increment for fast CPUs
AP_Compass: use apply_correction_function to eliminate duplication
AP_Compass: added some comments
Replay: fixed printf format
AP_Airspeed: fixed airspeed in Replay
Replay: update for new copter ATTITUDE message
AP_Math: refactor quaternion library
AP_NavEKF: Quaternion::to_euler now uses references instead of pointers
AP_Math: fix up rotation test suite
AP_Math: change quaternion class to use const references where optimal
AP_Math: expand frame transformation test case for quaternions
PX4: try starting the ll40ls on either I2C bus
AP_Buffer: remove scalar assignment so that non-scalars can be buffered