Updated to work with up to Julia version 1.9.1 and removed old requirements. Sees to work now with version 1.1.0-1.9.1, but I haven't tested every minor version in between. Most functionality should work for versions down to 0.7, but I won't certify that, and there are few dependencies that seem likely to cause problems in future releases, so should work with later version too.
Incorporated the new package structures, e.g. Project.toml and Manifest.toml, with separate dependencies for test and examples directories.
Reorganised to make it more obvious where to find things, like the test code, and the output figures.
Cleaned up a few minor issues, such as using BigInts in the DAG stats code for the number of paths, which can become very large.
Otherwise smoothed out some rough edges ready for the next generation of improvements.