AC_AttitudeControl_Heli: Remove ToDo.  Rate controllers should always run even if throttle is zero.
AP_MotorsHeli: Add To-Do. Swash setup hasn't seemed to work right for a while, this might be why.  Confirm later.
TradHeli: Force recalc scalers after setting main loop time in MotorsHeli so that ramp scalers are right for 32-bit.
Parameters: Update Tune Comments with new options
TradHeli: Move two static bools into heli_flags structure to save 2 bytes RAM.