Revert "removed sys-outs"

This reverts commit f09eb45c1bd04d9ecdd1dbda20f69b3dda6d1b11.
Revert "Filter gets applied when dataset changes."

This reverts commit 3d9cef62a50272f3bc268262741459f81615be13.
Revert "Filtering for students now respects the filter for materials"

This reverts commit ed078bf0763bfe520d43323b1149d09df2da28cd.
Revert "Quick and dirty fix for materials not showing correct in the beginning"

This reverts commit d9772e0b76f9ce1b18e47a597f14ab9479711c9a.
Revert "Added a selection for material type to student material selector"

This reverts commit 40b0060ca0d21edd7354283406afc59396b73773.
Merge pull request #509 from henningmu/issue#505

Reverted everything concerning the filtering for materials