agahirpa

The **self.var.downstruct** in [routing.py](https://github.com/ec-jrc/lisflood-code/blob/master/src/lisflood/hydrological_modules/routing.py) creates some negative values, which creates problem with lakes and reservoir modules. Is it reasonable to add the following self.var.downstruct[self.var.downstruct < 0] = maskinfo.info.mapC[0] after [self.var.downstruct[lddC...