simplifications. this commit is ignoring failing tests. the sortedPoly-algorithm has to be fixed for generic cases

# Conflicts:
#	ntrfc/postprocessing/turbo/bladeloading.py
#	ntrfc/utils/filehandling/mesh.py

This reverts commit 202d5900.

This reverts commit 4de463d6.

This reverts commit 24dbe257.

This reverts commit 33c61f49.

This reverts commit 0e1426c1.

(cherry picked from commit 4de463d6)

This reverts commit 24dbe257.

deleting all create_case-related tests as they are obsolete. similiar tests have to be implemented in ntrflows