Rover: Sail 3 position switch should disable motors not inhbit forward thrust.

[geofrancis]

I have been testing the sailing code with different motor configurations and I have found that the 3 position motorsail switch only inhibits forward propulsion, it doesn't disable the motors. This becomes a problem when its used in an omni configuration or a twin screw configuration as even in sail only mode its trying to use the bow and stern thrusters for yaw control and its trying to use the left and right main motors for yaw by running them in opposite directions.

there should be a bitmask for disabling motors when sailing so that the propellers arent turning at all when sailing unless in motor or motor assist mode or ideally 2 bit masks, one for motor only and one for motor assist. that way thrusters can be limited to motor only mode.

The main reason I am using this mode switch is to conserve battery power but that won't work if it's constantly running thrusters and main motors.