Motors spin slowly while disarmed

[EliotBR (Eliot)]

I just came across this while looking for something else, and thought I’d follow up that this is a solved problem now. Motor trim is available in ArduSub >= 4.5.3, by

@EliotBR

… setting the SERVOn_TRIM parameters for your motor pins …, with MOT_PWM_TYPE set to PWMAngle (9).