Before I go with a hammer to redesign these, I want to remove stuff that
does nothing first.
Hard-breaks API to allow rulesets to specify an enumerable of custom
sections rather than two specific weird ones.
For specific rulesets:
- osu!:
- Stack leniency slider merged into difficulty section.
- osu!taiko:
- Approach rate and circle size sliders removed.
- Colours section removed.
- osu!catch:
- No functional changes.
- osu!mania:
- Special style toggle merged into difficulty section.
- Colours section removed.
