Release2

See merge request geoq/gracetools!1

m-files in the release directory are now executable from the release
diretory. No need to change the path to the repo's root level.

- Add a shell script to get the example dataset.
- Update documentation: How to get the example data set.
- Fix an absolute path.

- Add readGFC function to be able to read gfc files with headers.
- Change link to the example dataset and add a description.
- Brush up README.md
- Update ignore list.