Previously, at minimum throttle, the quad would do absolutely no self-leveling

and simply run the motors at constant minthrottle.  This allowed the chance
for the quad to lose control during flight if the throttle was set to minimum,
say, to drop from a high altitude to a lower one.

With this edit, the quad will still self-level at minimum throttle when armed,
allowing for safe decents from altitude.  To prevent motors spinning when
arming/disarming, the yaw input is ignored if the throttle is at minimum and
we're using the sticks to arm/disarm.

Conflicts:
	src/main/flight/mixer.c

added cli command disable_pid_at_min_throttle

(same as previous)

src/main/config/config.c

@@ -380,6 +380,7 @@ static void resetConf(void)
     masterConfig.small_angle = 25;
     masterConfig.disable_pid_at_min_throttle = 0;
 
+
     masterConfig.airplaneConfig.flaps_speed = 0;
     masterConfig.airplaneConfig.fixedwing_althold_dir = 1;
 

src/main/flight/mixer.c

@@ -701,6 +701,8 @@ void mixTable(void)
                 if ((rcData[THROTTLE]) < rxConfig->mincheck) {
                     if (feature(FEATURE_MOTOR_STOP)) {
                         motor[i] = escAndServoConfig->mincommand;
+                    } else if (masterConfig.disable_pid_at_min_throttle != 0) {
+                        motor[i] = escAndServoConfig->minthrottle;
                     }
                 }
             }