Increase iTerm defaults slightly for 4.1

Increase iTerm defaults slightly for 4.1

The feed forward changes in 4.1 will bring, to all quads of reasonable control authority, reduced setpoint to gyro delay and less error.  iTerm will tend to accumulate less during fast inputs so there will be less of a problem with iTerm-windup and iTerm related bounce-back.

Higher I values lead to better control during tight turns and greater stability in wind.  Higher I doesn't increase the absolute amount of iTerm accumulating in the PID loop, but does allow it to change more quickly and to more quickly zero out the residual errors that are strong in tight turns.

I think this modest increase will optimise performance of the default 4.1 PIDs for most quads.

Lower authority quads will need to either reduce their I setting, or, preferably, lower the iterm_relax value to 10 or even 5, to avoid wind-up.