LICENSE: add an explicit ISC license.
The University of Bayreuth's homepage for symmetrica, http://www.algorithm.uni-bayreuth.de/en/research/SYMMETRICA/ states that "Symmetrica is public domain." However, that phrase links to a "Copyright Statement" page that almost verbatim reproduces the text of the ISC license: https://opensource.org/licenses/ISC To save time in the future, I've included the text of that license in a new LICENSE file in the repository.
LICENSE
0 → 100644