DistanceSensor, better way to handle out of range obstacles

[lukicdarkoo]

Currently, DistanceSensor returns a maximum value (wb_distance_sensor_get_max_value) with noise if object is too far (greater than the maximum value). Although this describes well analogue sensors, digital sensors usually have a way to handle these cases differently.

VL53L0X - ToF sensor in e-puck2
http://projects.gctronic.com/epuck2/doc/VL53L0X-UserManual-API.pdf - page 16, Table 1. Range Status
"Signal fail will trigger when the return signal is too low to give enough confidence on the range measured."
And here is the way it is handled in a library:
https://github.com/bitbank2/VL53L0X/blob/master/tof.c#L783
similar applies many digital sensors (including LiDARs).

Describe the solution you'd like
wb_distance_sensor_get_value can return -1 if the obstacle is out of range.

Describe alternatives you've considered
A separate function can be added that returns error code. This will allow users to have bad (unreliable) that still describes analogue sensors properly.

Additional context
Documentation should be slightly improved. The plot of noise (https://www.cyberbotics.com/doc/reference/distancesensor#lookup-table) should be named differently to emphasis it is a standard deviation.

For function wb_distance_sensor_get_max_value
https://www.cyberbotics.com/doc/reference/distancesensor#wb_distance_sensor_get_max_value
statement "returns the maximum value which can be returned by the distance sensor" is not current as the sensor can return higher values (maximum value + noise)

[omichel]

I believe
https://www.cyberbotics.com/doc/reference/distancesensor#wb_distance_sensor_get_max_value is correct and Webots should be fixed to ensure that the value returned by a distance sensor does not exceed the maximum value (the result should be clamped to the maximal value).