Refactor Cython routines to have same signatures as rust implementations

[MuellerSeb]

In order to have drop-in replacements for the Cython routines we need to refactor the existing cython routines:

• variogram
  • remove dim argument from directional, unstructured https://github.com/GeoStat-Framework/GSTools-Core/blob/afe9ec1134d19fc9bde8ae8466132433315718a0/src/variogram.rs#L240 https://github.com/GeoStat-Framework/GSTools-Core/blob/afe9ec1134d19fc9bde8ae8466132433315718a0/src/variogram.rs#L357

[LSchueler]

Closed with PR #215