GMT is an open source collection of about 80 command-line tools for
manipulating geographic and Cartesian data sets (including filtering,
trend fitting, gridding, projecting, etc.) and producing PostScript
illustrations ranging from simple x-y plots via contour maps to
artificially illuminated surfaces and 3D perspective views; the GMT
supplements add another 40 more specialized and discipline-specific
tools.

By default, GMT will use Dave Watson's Delaunay triangulation routine.
However, a much faster alternative is available from Jonathan Shewchuk,
but his routine is not distributed under the GNU Public License.
In order to use the Shewchuk's routine you have to launch the script
by passing the SHEWCHUK parameter:

  SHEWCHUK=yes ./GMT.SlackBuild

For more details refer to the README and LICENSE.TXT files contained
into the GMT sources.