Update treewidth

[smaniu]

Updated treewidth:

• added CI workflows for Linux and MacOS, to replace the obsolete Travis
• reorganised the code in folders
• added Catch2 test and replaced make with CMake
• added correct link to Zenodo datasets instead of the dead institutional link

[Copilot]

Pull request overview

This PR modernizes the treewidth project by migrating away from Travis/Make-based builds to a CMake + GitHub Actions setup, reorganizing the code under include/treewidth/ + src/, and introducing a Catch2-based CTest suite to validate core graph operations and decomposition behavior.

Changes:

• Replace Make/Travis with CMake build + GitHub Actions CI for Linux and macOS (including sanitizer builds).
• Add a Catch2 test suite (graph ops, upper/lower bounds, decomposition serialization/validation).
• Reorganize implementation into header-based components under include/treewidth/ and a new src/main.cpp CLI.

Reviewed changes

Copilot reviewed 16 out of 33 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
tests/test_upper.cpp	Adds upper-bound tests and decomposition validity checks.
tests/test_serialization.cpp	Adds serialization tests for Bag and decomposition header.
tests/test_lower.cpp	Adds lower-bound tests and documents excluded buggy paths.
tests/test_graph.cpp	Adds unit tests for Graph operations (add/remove/fill/contract).
tests/graph_builders.h	Adds deterministic in-process graph constructors for tests.
tests/decomposition_check.h	Adds .dec parser + tree decomposition property validation.
tests/CMakeLists.txt	Defines the Catch2 test executable and registers it with CTest.
tests/catch_main.cpp	Provides the Catch2 main translation unit.
src/main.cpp	Introduces the CLI entrypoint for upper/lower bound computation.
README.md	Updates build/test instructions and CI badges for the new toolchain.
Makefile	Removes obsolete Makefile build.
include/treewidth/TreeDecomposition.h	Makes operator<< inline for header inclusion safety.
include/treewidth/PermutationStrategy.h	Adds permutation strategy base for heuristics.
include/treewidth/MetaLowerBoundHeuristic.h	Adds base type for meta lower-bound heuristics.
include/treewidth/MCSPermutationStrategy.h	Adds MCS permutation strategy (currently problematic).
include/treewidth/LowerBoundMMD.h	Adds MMD lower-bound implementation.
include/treewidth/LowerBound.h	Adds lower-bound interfaces + MMD+ implementation.
include/treewidth/LBNPlus.h	Adds LBN+ meta heuristic.
include/treewidth/LBN.h	Adds LBN meta heuristic.
include/treewidth/Graph.h	Adds Graph implementation used across algorithms and tests.
include/treewidth/FillInPermutationStrategy.h	Adds min-fill-in permutation strategy.
include/treewidth/Delta2D.h	Adds Delta2D lower-bound implementation.
include/treewidth/DegreePermutationStrategy.h	Adds min-degree permutation strategy.
include/treewidth/DegreeFillInPermutationStrategy.h	Adds degree+fill-in permutation strategy.
include/treewidth/common.h	Adds timestamp helper for CLI timing output.
include/treewidth/CE.h	Adds contraction engine used by some meta heuristics.
include/treewidth/Bag.h	Makes operator<< inline for header inclusion safety.
CMakeLists.txt	Adds top-level CMake project, library target, executable, tests, sanitizers.
.travis.yml	Removes obsolete Travis CI configuration.
.gitignore	Adds ignores for build outputs and local notes/docs.
.github/workflows/ci-macos.yml	Adds macOS CI workflow for build/test + sanitizers.
.github/workflows/ci-linux.yml	Adds Linux CI workflow (gcc/clang matrix) for build/test + sanitizers.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.