Fixed crashes when dir parallel to z axis

[jovoy]

[jgalan]

This PR is 35 commits behind master, thats probably the reason why the pipeline is failing.

You should merge master in your local branch true_wolter_interaction and then push it.

git merge origin/master
git push

Sometimes it might be required to change to the local master and pull it.

git checkout master
git pull
git checkout true_wolter_interaction
git merge master
git push