When autotagging based on path, return empty set (instead of a set
containing an empty string) when no tag can be found. E.g the
path "D:\" has no grand-parent.
Change initial directory in import form. If all zips are in the
same directory (or the same grand-parent directory), use the common
directory as a start. If no such directory exists, see if there is
something in the clipboard.
Enlarge try-catch block when importing.
Handle the case where the user wants to import all zips in the root
of a disk, and she writes "D:" instead of "D:\".
Move "All subfolders" radio button to top since it is the default.