Using gunzip instead of uncompress

[(Raphael Quinet)]

If you want to reduce the amount of disk space used by the maps,
you should consider using GNU Zip/UnZip instead of compress/
uncompress.  The standard maps distribution takes less than 2000K
when compressed with gzip.

I have uploaded a small patch (for common/map.c) in the 'incoming'
directory.

Comments are welcome.

                                    Raphael Quinet