Investigate how gain and offset is utilized for rave-overshooting (poo)

[UlfNordh]

When viewed in e.g. baltrad-viewer the detectability field seems inverted i.e. areas with high poo is transparent and areas with low, or no poo, is coloured gray, this is inverted relative e.g. fields for bropo (anomalies) and beamb (blockage).
It needs to be investigated how gain and offset is used for rave-overshooting (poo). For polar scan gain = -0.00392156862745098 and offset = 1.0, while for cartesian data, gain = 0.00392156862745098 and offset = 0. It might be so from "historical" reasons, what's important is that the code reading the products can handle it correctly.