Log message:
Actually netpbm is not needed in buildlink3.mk

Log message:
GTS stands for the GNU Triangulated Surface Library. It provides a set of
useful functions to deal with 3D surfaces meshed with interconnected
triangles.

A brief summary of its main features:
* Simple object-oriented structure giving easy access to topological
  properties.
* 2D dynamic Delaunay and constrained Delaunay triangulations.
* Robust geometric predicates (orientation, in circle) using fast adaptive
  floating point arithmetic.
* Robust set operations on surfaces (union, intersection, difference).
* Surface refinement and coarsening (multiresolution models).
* Dynamic view-independent continuous level-of-detail.
* Preliminary support for view-dependent level-of-detail.
* Bounding-boxes trees and Kd-trees for efficient point location and
  collision/intersection detection.
* Graph operations: traversal, graph partitioning.
* Metric operations (area, volume, curvature ...).
* Triangle strips generation for fast rendering.