Copter: remove unused var from ekf check
Copter: of-loiter unavailable if OPTFLOW not enabled

of-loiter was small but still present even when optflow was disabled
Copter: disable parachute and rally on APM1
Copter: remove empty Telemetry.pde
Copter: remove unused local var from Flip
Copter: remove ch6 tuning of INAV_TC

Users normally never change these parameters and if by chance they do want
to, they can set them before flying
InertialNav: remove accessor to set time_constants
DataFlash: typo fix in ListAvailableLogs