The source files located in this directory are optional and not mandatory for
standard Gmsh use. They are provided for convenience and are each covered by
their own respective license:

* ALGLIB: GNU General Public License (GPL) v. 2 or later
* ANN: GNU Lesser General Public License
* BoundaryLayers: GNU Affero General Public License (AGPL) v. 3 or later
* DiscreteIntegration: MIT/X11 License
* HighOrderMeshOptimizer: MIT/X11 License
* MathEx: GNU Lesser General Public License (LGPL) v. 2.1 or later, with static
  linking exception
* MeshOptimizer: MIT/X11 License
* MeshQualityOptimizer: MIT/X11 License
* Netgen: GNU Lesser General Public License (LGPL) v. 2.1
* QuadMeshingTools: Gmsh License
* QuadTri: Gmsh License
* Revoropt/include/Revoropt: Mozilla Public License (MPL) v. 2.0
* WinslowUntangler: Gmsh license
* bamg: GNU Lesser General Public License (LGPL) v. 2.1 or later
* blossom: Gmsh License
* domhex: Gmsh License
* eigen: BSD License
* gmm: GNU Lesser General Public License (LGPL), v. 3 or later
* hxt: GNU General Public License (GPL) v. 2 or later, with exception for
  linking with Gmsh under Gmsh license
* kbipack: GNU General Public License (GPL) v. 2 or later
* metis: Apache License (APL), v. 2.0
* mobile: GNU General Public License (GPL), v. 2 or later
* mpeg_encode: freely distributed, but patents are held by several companies on
  various aspects of the MPEG video standard
* nii2mesh: BSD License
* onelab: MIT/X11 License
* tinyobjloader: MIT License
* tinyxml2: Zlib License
* untangle: No license, freely available for non-commercial purposes
* voro++: BSD-type License
* zipper: Zlib License

See each subdirectory for the detailed license terms.

Set the ENABLE_SYSTEM_CONTRIB cmake option to use system versions of these
libraries, when possible.
