canonaut — Rust port of nauty and Traces

This crate is derived from nauty and Traces (https://pallini.di.uniroma1.it/),
version 2.6 and later, licensed under the Apache License, Version 2.0.

Original copyright holders:
  Copyright (c) Brendan McKay, Australian National University (1984-)
  Copyright (c) Adolfo Piperno, University of Rome "Sapienza" (2008-)
  Copyright (c) Gunnar Brinkmann, University of Ghent (2009-)
  Copyright (c) Magma project, University of Sydney
  Copyright (c) Sampo Niskanen and Patric Östergård
