Add watervisibility QA to the system

[Rezenders]

• how to simulate watervisibility?
• implement watervisibility observer

[Rezenders]

period = 2pi/B amplitude = max_water_visibility - min_water_visibility water_visibility = amplitude sin(B*x) + min_water_visibility

[Rezenders]

Should the water visibility vary according to the position of the robot or the time?

[Rezenders]

t = current_time - self.initial_time
        v_delta = water_visibility_amp + water_visibility_min
        water_visibility = water_visibility_amp * math.cos(
            (2*math.pi/water_visibility_period)*t) + v_delta