* Change slider drop penalty to use actual number of difficult sliders, fix slider nerf being too lenient
* Move cubing to performance calculation
* Add separate list for slider strains
* Rename difficulty atttribute
* Rename attribute in perfcalc
* Check if AimDifficultSliderCount is more than 0, code quality fixes
* Add `AimDifficultSliderCount` to the list of databased attributes
* Code quality
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Co-authored-by: James Wilson <tsunyoku@gmail.com>