Group folders in file dialogs
Since the multiblock writer writes a folder for each time step plus the *.vtm file the output folder has a huge number of folders and files in it. Since the vtm files are of type name_000000.vtm they are grouped together. However, the folders of type name_000000 are not grouped and thus occupy a large amount of space in the file dialogs. It would be nice if those folders would be grouped together as well to increase the readability of folder content.