Minimum distance for tour generation

[NinaWie]

In the tour generation PR we discussed about the possibility of a minimum-distance parameter for tours. This would prevent the creation of tours that are only artifacts in the data, for example when one location is regarded as two separate locations.

We would have to input the triplegs and then take the sum over the tripleg distances. We should discuss whether we need this feature and, if yes, whether it should be implemented in the tour generation or as a post-processing step.