To install
1) Download & compile sdts2dem from
	http://www.cs.arizona.edu/projects/topovista/sdts2dem/
2) Copy sdts2dem to somewhere in your path
3) Make sure you have the Perl module WWW::Mechanize
4) Keep the three files -- dem24k.pl, dem24k.dat, and repackage.sh
	together in the same directory and add this directory to your path.
	Then try downloading DEM tiles in Viking (they take a while to download)
	(TODO: easier way)

TODO: download in appropriate dir (nto always ~/.viking_maps)
	need to pass along dir from Viking and escape special chars
