While it is the case for the existing official Skills, Skill implementations shouldn't be required to conform to a strain based approach.
There are other valid approaches to calculating skill difficulty that can be supported by abstracting the strain logic into its own StrainSkill class.
As strains are an implementation detail of the current Skill calculations, it makes sense that strain related logic should be encapsulated within the Skill class.
Although this isn't necessary for existing official rulesets and calculators, custom calculators can have use cases for accessing mods in difficulty calculation.
For example, accounting for the effects of visual mods.
There were two coordinate systems used:
- 0..512 (used in osu!stable)
- 0..1 (relative coordinate)
This commit replaces the usage of
the relative coordinate system to
the coordinate system of 0..512.
