PathCompression

[JonasLukasczyk]

When running the Path Compression filter with only descending segmentation on and ascending manifold / Morse-Smale segmentation off paraview crashes with a segfault. When ascending/descending segmentation is on and Morse-Smale off it works. @m-s-will

[m-s-will]

The current PathCompression will soon be superseded/fixed by the distributed Version, then this shouldn't happen anymore.
Current workaround is to just compute both segmentations.