Resolve "Adapt `MeshModel` to visitors"

Closes #28

See merge request grp-fidentis/analyst2!29

Resolve "Refactor package `symmetry` in the `Comparison` module"

Closes #27

See merge request grp-fidentis/analyst2!27

Issue 26 done

See merge request grp-fidentis/analyst2!25

The code of Matej re-entered

See merge request grp-fidentis/analyst2!23

Revert "Merge branch 'issue22' into 'master'"

See merge request grp-fidentis/analyst2!21

This reverts merge request !20

Issue22

See merge request grp-fidentis/analyst2!20

Resolve "Separate (external) interfaces form implementation for MeshModel"

Closes #25

See merge request grp-fidentis/analyst2!17

Code adapted to new API of the MeshModel. Weird usage MeshPoints replaced with using Vector3d. Additional refactorig would be helpful