Michael Riepe (riepe@ifwsn4.ifw.uni-hannover.de) has send me a patch
to support sparse files with tar on Linux boxes.

I did'nt have any experience with it and unfortunately dds2tar doesn't support
sparse files. But if you are familar with patching tar, you may decide
to include this patch also.

Please send comments on that patch to Michael. J"org.