Smet file with different resolutions
When a smet file contains parameters at different time resolution, some parameters will have quite a lot of nodata (ie 3 hours ILWR in an otherwise 30' file), the low resolution parameter is not plotted with a continuous line (because of all the nodata in between). On one hand, it is valuable to be able to ""see"" the nodata, on the other hand it would be nice to have a way to force interpolating over the nodata (or show the data as discontinuous points).