Preflibtools

**Full Changelog**: https://github.com/PrefLib/preflibtools/compare/v2.0.7...v2.0.08

What's Changed
* Small improvements for writing preflib files and CategoricalInstance by martinlackner in https://github.com/PrefLib/preflibtools/pull/1
* Handling of spaces in preflib files by martinlackner in https://github.com/PrefLib/preflibtools/pull/3

New Contributors
* martinlackner made their first contribution in https://github.com/PrefLib/preflibtools/pull/1

**Full Changelog**: https://github.com/PrefLib/preflibtools/compare/v2.0.6...v2.0.7

I know it's bad to publish that many releases, sorry for that :p

After adding unit tests, I found several bugs in the instance handling. Those are corrected now.